Comment 4 for bug 1641661

I've tested xenial using curtin vmtest, which includes several installations
including one that has been made to show this failure.

I'm attaching the vmtest output directory for full logs.

$ git clone https://gist.github.com/4e25b5a9e6245692be90098464990d00.git vtools
$ export PATH=$PWD/vtools:$PATH

$ bzr branch curtin trunk
$ cd trunk
$ bzr revno
443

$ rel=xenial
$ cname=test-$rel;
$ setup-curtin-container --proposed ubuntu-daily:$rel $cname
Creating test-xenial
...

$ lxc exec $cname apt-cache policy curtin
curtin:
  Installed: 0.1.0~bzr437-0ubuntu1~16.04.1
  Candidate: 0.1.0~bzr437-0ubuntu1~16.04.1
  Version table:
 *** 0.1.0~bzr437-0ubuntu1~16.04.1 500
        500 http://archive.ubuntu.com/ubuntu xenial-proposed/universe amd64 Packages
        100 /var/lib/dpkg/status
     0.1.0~bzr425-0ubuntu1~16.04.1 500
        500 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages
     0.1.0~bzr365-0ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages

$ PATH=$PWD/../vtools:$PATH \
    CURTIN_VMTEST_CURTIN_EXE="curtin-from-container $cname curtin" \
    CURTIN_VMTEST_TOPDIR=$PWD/$rel-1641661 \
    ./tools/jenkins-runner \
     tests/vmtests/test_mdadm_bcache.py
...........
----------------------------------------------------------------------
Ran 196 tests in 4012.451s
OK
Tue, 31 Jan 2017 22:14:21 +0000: vmtest end [0] in 4014s