diff -Nru autopkgtest-2.11/debian/changelog autopkgtest-2.12/debian/changelog
--- autopkgtest-2.11/debian/changelog	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/debian/changelog	2014-03-31 09:45:17.000000000 +0000
@@ -1,3 +1,33 @@
+autopkgtest (2.12) unstable; urgency=medium
+
+  [ Martin Pitt ]
+  New features:
+  * Add new options -s/--shell-fail for running a shell in the testbed after
+    every failed test, and --shell for running a shell in the testbed after
+    every test. This should make debugging tests or regressions quite a bit
+    simpler. This actually spawns a shell for the null, chroot, schroot, and
+    lxc runners, and shows how to login to the VM for qemu (this will
+    hopefully be improved in the future, but at least makes debugging possible
+    for now).
+
+  Bug fixes:
+  * adt-build-lxc: Fix apt proxy setting for ubuntu template; use $HTTP_PROXY,
+    not $APT_PROXY.
+  * Make PEP-8 failures non-fatal during package build. They often fail in
+    backports to old releases, and running them before releasing a new package
+    is sufficient.
+  * Filter out comment lines from control lines, as python-debian doesn't
+    properly do that (Debian #743174). Fixes lintian autopkgtest.
+    (LP: #1300031)
+
+  [ Antonio Terceiro ]
+  * adt-virt-schroot: Add new option -s/--session-id for specifying a custom
+    schroot session id. This is useful for debugging test suites that go crazy
+    on ci.debian.net, so you can `schroot --list --all-sessions` and see which
+    sessions are still open.
+
+ -- Martin Pitt <mpitt@debian.org>  Mon, 31 Mar 2014 11:45:13 +0200
+
 autopkgtest (2.11) unstable; urgency=medium
 
   * Add tools/adt-setup-vm: Setup script for vmdebootstrap (and potentially
diff -Nru autopkgtest-2.11/debian/rules autopkgtest-2.12/debian/rules
--- autopkgtest-2.11/debian/rules	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/debian/rules	2014-03-31 09:45:17.000000000 +0000
@@ -45,7 +45,7 @@
 
 override_dh_auto_test:
 	tests/pyflakes
-	tests/pep8
+	tests/pep8 || true
 	tests/adt-run NullRunnerNoRoot
 
 # necessary until we move to compat level 9
diff -Nru autopkgtest-2.11/doc/README.virtualisation-server autopkgtest-2.12/doc/README.virtualisation-server
--- autopkgtest-2.11/doc/README.virtualisation-server	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/doc/README.virtualisation-server	2014-03-31 09:45:17.000000000 +0000
@@ -260,7 +260,16 @@
   and then the regime server exits with status 0, after
   closing the testbed if applicable.
 
+* Command
+	shell
+  response: one of
+	ok
+	not supported by virt server
 
+  Runs a shell in the testbed (as root, if available), while the testbed is
+  open. This is intended for interactively debugging problems with tests. The
+  virt server has to provide a hook_shell() function for this, otherwise this
+  command is not supported.
 
 
 On any error including signals to the regime server or EOF on stdin
diff -Nru autopkgtest-2.11/lib/VirtSubproc.py autopkgtest-2.12/lib/VirtSubproc.py
--- autopkgtest-2.11/lib/VirtSubproc.py	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/lib/VirtSubproc.py	2014-03-31 09:45:17.000000000 +0000
@@ -594,6 +594,16 @@
     copyupdown(c, ce, True)
 
 
+def cmd_shell(c, ce):
+    cmdnumargs(c, ce, 4)
+    if not downtmp:
+        bomb("`shell' when not open")
+    try:
+        caller.hook_shell(c[1], c[2], c[3], c[4])
+    except AttributeError:
+        raise FailedCmd(['not supported by virt server'])
+
+
 def command():
     sys.stdout.flush()
     while True:
diff -Nru autopkgtest-2.11/runner/adt-run autopkgtest-2.12/runner/adt-run
--- autopkgtest-2.11/runner/adt-run	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/runner/adt-run	2014-03-31 09:45:17.000000000 +0000
@@ -384,6 +384,10 @@
                       help='command to gain root during package build, passed to dpkg-buildpackage -r')
     parser.add_option('-q', '--quiet', action='store_true', dest='quiet', default=False)
     parser.add_option('-d', '--debug', action='count', dest='debuglevel', default=0)
+    parser.add_option('-s', '--shell-fail', action='store_true',
+                      help='run a shell in the testbed after every failed test')
+    parser.add_option('--shell', action='store_true',
+                      help='run a shell in the testbed after every test')
     parser.add_option('--gnupg-home', type='string', dest='gnupghome',
                       default='~/.autopkgtest/gpg',
                       help='use GNUPGHOME rather than ~/.autopkgtest (for'
@@ -1387,6 +1391,7 @@
 
         self._debug(' - - - - - - - - - - results - - - - - - - - - -')
 
+        passed = False
         if rc != 0:
             self.reportfail('non-zero exit status %d' % rc)
         elif se_size != 0 and 'allow-stderr' not in self.restriction_names:
@@ -1395,6 +1400,7 @@
             self.reportfail('status: %d, stderr: %s' % (rc, stderr_top))
         else:
             self.report('PASS')
+            passed = True
 
         # avoid mixing up stdout (from report) and stderr (from _debug) in output
         sys.stdout.flush()
@@ -1427,6 +1433,13 @@
             if not os.listdir(ap.host):
                 os.rmdir(ap.host)
 
+        if opts.shell or (opts.shell_fail and not passed):
+            self._debug(' - - - - - - - - - - running shell - - - - - - - - - -')
+            testbed.command('shell', (os.path.realpath('/dev/stdin'),
+                                      os.path.realpath('/dev/stdout'),
+                                      os.path.realpath('/dev/stderr'),
+                                      tree.tb))
+
 
 def read_stanzas(path):
     stanzas = []
@@ -1438,13 +1451,25 @@
             raise
         return []
 
+    # filter out comments, python-debian doesn't do that
+    # (http://bugs.debian.org/743174)
+    lines = []
+    for l in control:
+        # completely ignore ^# as that breaks continuation lines
+        if l.startswith('#'):
+            continue
+        # filter out comments which don't start on first column
+        l = l.split('#', 1)[0]
+        lines.append(l)
+    control.close()
+
     lno = 0
     stz = {}  # stz[field_name][index] = (lno, value)
                 # special field names:
                 # stz[' lno'] = number
                 # stz[' tests'] = list of Test objects
                 # empty dictionary means we're between stanzas
-    for paragraph in deb822.Deb822.iter_paragraphs(control):
+    for paragraph in deb822.Deb822.iter_paragraphs(lines):
         lno += 1
         stz = {' lno': lno, ' tests': []}
         for field, value in paragraph.iteritems():
diff -Nru autopkgtest-2.11/runner/adt-run.1 autopkgtest-2.12/runner/adt-run.1
--- autopkgtest-2.11/runner/adt-run.1	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/runner/adt-run.1	2014-03-31 09:45:17.000000000 +0000
@@ -190,6 +190,15 @@
 additional \fB-d\fR increases the debugging level; the current maximum
 is \fB-ddd\fR.  If you like to see what's going on, \fR-d\fB or
 \fR-dd\fB is recommended.
+
+.TP
+.BR --shell-fail | -s
+Run an interactive shell in the testbed after every failed test.
+
+.TP
+.BR --shell
+Run an interactive shell in the testbed after every test.
+
 .TP
 .BI --gnupg-home= dir
 Uses \fIdir\fR as the \fBGNUPGHOME\fR for local apt archive signing.
diff -Nru autopkgtest-2.11/tests/adt-run autopkgtest-2.12/tests/adt-run
--- autopkgtest-2.11/tests/adt-run	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/tests/adt-run	2014-03-31 09:45:17.000000000 +0000
@@ -896,13 +896,15 @@
         '''test depends on build dependencies'''
 
         p = self.build_src('''Tests: pass
-Depends: @, testdep1, @builddeps@, testdep2
+Depends: @, testdep1, @builddeps@, testdep2,
+# blabla
+ testdep3
 Restrictions: needs-root
 ''', {'pass': '#!/bin/sh\ntrue'})
 
         # add extra build dependencies to testpkg
-        subprocess.check_call(['sed', '-i', '/^Build-Depends:/ s/:.*/: bdep1 , bdep2\\n'
-                                            'Build-Depends-Indep: bdep3/',
+        subprocess.check_call(['sed', '-i', '/^Build-Depends:/ s/:.*/: bdep1 , bdep2,\\n bdep3, # moo\\n#comment\\n bdep4\\n'
+                                            'Build-Depends-Indep: bdep5/',
                                os.path.join(p, 'debian', 'control')])
 
         (code, out, err) = self.adt_run(['-dB', '--unbuilt-tree=' + p],
@@ -915,8 +917,11 @@
         self.assertIn('synthesised dependency bdep1\n', err)
         self.assertIn('synthesised dependency bdep2\n', err)
         self.assertIn('synthesised dependency bdep3\n', err)
+        self.assertIn('synthesised dependency bdep4\n', err)
+        self.assertIn('synthesised dependency bdep5\n', err)
         self.assertIn('processing dependency testdep2\n', err)
-        self.assertRegex(err, 'fake-apt-get: .*install.*testpkg testdep1 bdep1 bdep2 bdep3 make testdep2')
+        self.assertIn('processing dependency testdep3\n', err)
+        self.assertRegex(err, 'fake-apt-get: .*install.*testpkg testdep1 bdep1 bdep2 bdep3 bdep4 bdep5 make testdep2 testdep3')
 
     def test_logfile(self):
         '''--log-file option'''
diff -Nru autopkgtest-2.11/tools/adt-build-lxc autopkgtest-2.12/tools/adt-build-lxc
--- autopkgtest-2.11/tools/adt-build-lxc	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/tools/adt-build-lxc	2014-03-31 09:45:17.000000000 +0000
@@ -37,6 +37,7 @@
 LXCDIR=`lxc-config lxc.lxcpath` || LXCDIR=`lxc-config lxcpath` || LXCDIR=/var/lib/lxc
 
 LXC_ARGS="-t $DISTRO -- -r $RELEASE"
+export HTTP_PROXY=${HTTP_PROXY:=apt}
 
 setup() {
     # add deb-src
@@ -63,11 +64,11 @@
 
 if [ ! -e $LXCDIR/$NAME ]; then
     # first-time run: just create the container
-    APT_PROXY=apt lxc-create -n $NAME $LXC_ARGS
+    lxc-create -n $NAME $LXC_ARGS
     setup $NAME
 else
     # create a new rootfs in a temp container
-    APT_PROXY=apt lxc-create -n ${NAME}.new $LXC_ARGS -F
+    lxc-create -n ${NAME}.new $LXC_ARGS -F
     setup ${NAME}.new
     # replace the original rootfs
     rsync -aHAXS --numeric-ids --delete $LXCDIR/${NAME}.new/rootfs $LXCDIR/${NAME}/rootfs
diff -Nru autopkgtest-2.11/tools/adt-buildvm-ubuntu-cloud autopkgtest-2.12/tools/adt-buildvm-ubuntu-cloud
--- autopkgtest-2.11/tools/adt-buildvm-ubuntu-cloud	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/tools/adt-buildvm-ubuntu-cloud	2014-03-31 09:45:17.000000000 +0000
@@ -116,8 +116,8 @@
             if percent > download_image.lastpercent:
                 download_image.lastpercent = percent
                 sys.stdout.write('\r%.1f/%.1f MB (%i%%)                 ' % (
-                    cur_bytes/1000000.,
-                    totalsize/1000000.,
+                    cur_bytes / 1000000.,
+                    totalsize / 1000000.,
                     percent))
                 sys.stdout.flush()
         else:
diff -Nru autopkgtest-2.11/virt-subproc/adt-virt-chroot autopkgtest-2.12/virt-subproc/adt-virt-chroot
--- autopkgtest-2.11/virt-subproc/adt-virt-chroot	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/virt-subproc/adt-virt-chroot	2014-03-31 09:45:17.000000000 +0000
@@ -24,6 +24,7 @@
 
 import sys
 import os
+import subprocess
 from optparse import OptionParser
 
 try:
@@ -110,5 +111,14 @@
 def hook_capabilities():
     return capabilities
 
+
+def hook_shell(stdin, stdout, stderr, dir):
+    with open(stdin, 'rb') as sin:
+        with open(stdout, 'wb') as sout:
+            with open(stderr, 'wb') as serr:
+                subprocess.call(VirtSubproc.down + ['sh', '-c', 'cd %s; exec bash -i' % dir],
+                                stdin=sin, stdout=sout, stderr=serr)
+
+
 parse_args()
 VirtSubproc.main()
diff -Nru autopkgtest-2.11/virt-subproc/adt-virt-lxc autopkgtest-2.12/virt-subproc/adt-virt-lxc
--- autopkgtest-2.11/virt-subproc/adt-virt-lxc	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/virt-subproc/adt-virt-lxc	2014-03-31 09:45:17.000000000 +0000
@@ -250,5 +250,15 @@
     return capabilities
 
 
+def hook_shell(stdin, stdout, stderr, dir):
+    argv = ['lxc-attach', '-n', lxc_container_name, '--', 'sh', '-c', 'cd %s; exec bash -i' % dir]
+    if use_sudo:
+        argv = ['sudo', '-E'] + argv
+    with open(stdin, 'rb') as sin:
+        with open(stdout, 'wb') as sout:
+            with open(stderr, 'wb') as serr:
+                subprocess.call(argv, stdin=sin, stdout=sout, stderr=serr)
+
+
 parse_args()
 VirtSubproc.main()
diff -Nru autopkgtest-2.11/virt-subproc/adt-virt-null autopkgtest-2.12/virt-subproc/adt-virt-null
--- autopkgtest-2.11/virt-subproc/adt-virt-null	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/virt-subproc/adt-virt-null	2014-03-31 09:45:17.000000000 +0000
@@ -24,6 +24,7 @@
 
 import sys
 import os
+import subprocess
 from optparse import OptionParser
 
 try:
@@ -81,5 +82,14 @@
 def hook_capabilities():
     return capabilities
 
+
+def hook_shell(stdin, stdout, stderr, dir):
+    with open(stdin, 'rb') as sin:
+        with open(stdout, 'wb') as sout:
+            with open(stderr, 'wb') as serr:
+                subprocess.call(['bash', '-i'], stdin=sin, stdout=sout,
+                                stderr=serr, cwd=dir)
+
+
 parse_args()
 VirtSubproc.main()
diff -Nru autopkgtest-2.11/virt-subproc/adt-virt-qemu autopkgtest-2.12/virt-subproc/adt-virt-qemu
--- autopkgtest-2.11/virt-subproc/adt-virt-qemu	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/virt-subproc/adt-virt-qemu	2014-03-31 09:45:17.000000000 +0000
@@ -351,5 +351,22 @@
     return caps
 
 
+def hook_shell(stdin, stdout, stderr, dir):
+    with open(stdout, 'w') as f:
+        f.write('''You can now log into the VM through the serial terminal.
+Depending on which terminal program you have installed, you can use one of
+
+    minicom -D unix#%(tty0)s
+    nc -U %(tty0)s
+    socat - UNIX-CONNECT:%(tty0)s
+
+The tested source package is in %(dir)s
+
+Press Enter to resume adt-run.
+''' % {'tty0': os.path.join(workdir, 'ttyS0'), 'dir': dir})
+    with open(stdin, 'r') as f:
+        f.readline()
+
+
 parse_args()
 VirtSubproc.main()
diff -Nru autopkgtest-2.11/virt-subproc/adt-virt-schroot autopkgtest-2.12/virt-subproc/adt-virt-schroot
--- autopkgtest-2.11/virt-subproc/adt-virt-schroot	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/virt-subproc/adt-virt-schroot	2014-03-31 09:45:17.000000000 +0000
@@ -27,6 +27,7 @@
 import re
 import grp
 import pwd
+import subprocess
 from optparse import OptionParser
 
 try:
@@ -65,17 +66,21 @@
 
 
 def parse_args():
-    global schroot
+    global schroot, sessid
 
     usage = "%prog [<options>] <schroot>"
     parser = OptionParser(usage=usage)
 
     parser.add_option('-d', '--debug', action='store_true')
+    parser.add_option('-s', '--session-id',
+                      help='custom schroot session ID for easy identification '
+                      'in "schroot --list --all-sessions"')
 
     (opts, args) = parser.parse_args()
     if len(args) != 1:
         parser.error("need exactly one arg, schroot name")
 
+    sessid = opts.session_id
     schroot = args[0]
 
     info = VirtSubproc.execute('schroot --config -c', [schroot],
@@ -110,7 +115,8 @@
 def hook_open():
     global schroot, sessid
     sessid = VirtSubproc.execute(
-        'schroot -b -c', [schroot], downp=False, outp=True)
+        'schroot -b -c', [schroot] + (sessid and ['-n', sessid] or []),
+        downp=False, outp=True)
     VirtSubproc.down = ['schroot', '-r', '-d', '/', '-c', sessid]
     if 'root-on-testbed' in capabilities:
         VirtSubproc.down += ['-u', 'root']
@@ -157,5 +163,16 @@
 def hook_capabilities():
     return capabilities
 
+
+def hook_shell(stdin, stdout, stderr, dir):
+    argv = ['schroot', '-r', '-d', dir, '-c', sessid]
+    if 'root-on-testbed' in capabilities:
+        argv += ['-u', 'root']
+    with open(stdin, 'rb') as sin:
+        with open(stdout, 'wb') as sout:
+            with open(stderr, 'wb') as serr:
+                subprocess.call(argv, stdin=sin, stdout=sout, stderr=serr)
+
+
 parse_args()
 VirtSubproc.main()
diff -Nru autopkgtest-2.11/virt-subproc/adt-virt-schroot.1 autopkgtest-2.12/virt-subproc/adt-virt-schroot.1
--- autopkgtest-2.11/virt-subproc/adt-virt-schroot.1	2014-03-21 08:36:58.000000000 +0000
+++ autopkgtest-2.12/virt-subproc/adt-virt-schroot.1	2014-03-31 09:45:17.000000000 +0000
@@ -38,6 +38,12 @@
 
 .SH OPTIONS
 .TP
+.BI -s " ID" " | --session-id=" ID
+Use a custom schroot session ID. This allows the user to easily
+identify hung sessions in
+.B schroot --list --all-sessions\fR.
+
+.TP
 .BR \-d " | " \-\-debug
 Enables debugging output.