Network is unreachable errno string reported in various ways killing pip and git operations gate/check jobs

The "Network is unreachable" errno string reported in various ways killing pip and git operations gate/check jobs. It seems to be reported mostly with pip, accessing pypi.openstack.org, sometimes with git.openstack.org, and less often with others.

One example of how it manifests itself is killing pip installs (see: http://logs.openstack.org/91/70691/2/check/check-devstack-dsvm-cells/9dd947b/console.html):

2014-02-03 11:09:07.482 | 2014-02-03 11:09:07 + sudo PIP_DOWNLOAD_CACHE=/var/cache/pip HTTP_PROXY= HTTPS_PROXY= NO_PROXY= /usr/local/bin/pip install --build=/tmp/pip-build.GGbB5 -e /opt/stack/new/horizon
2014-02-03 11:09:07.482 | 2014-02-03 11:09:07 Obtaining file:///opt/stack/new/horizon
2014-02-03 11:09:07.483 | 2014-02-03 11:09:07 Running setup.py egg_info for package from file:///opt/stack/new/horizon
2014-02-03 11:09:07.483 | 2014-02-03 11:09:07 [pbr] Processing SOURCES.txt
2014-02-03 11:09:07.483 | 2014-02-03 11:09:07 warning: LocalManifestMaker: standard file '-c' not found
2014-02-03 11:09:07.484 | 2014-02-03 11:09:07
2014-02-03 11:09:07.514 | 2014-02-03 11:09:07 [pbr] In git context, generating filelist from git
2014-02-03 11:09:07.514 | 2014-02-03 11:09:07 warning: no files found matching 'AUTHORS'
2014-02-03 11:09:07.515 | 2014-02-03 11:09:07 warning: no files found matching 'ChangeLog'
2014-02-03 11:09:07.515 | 2014-02-03 11:09:07 warning: no previously-included files matching '*.pyc' found anywhere in distribution
2014-02-03 11:09:07.516 | 2014-02-03 11:09:07 warning: no files found matching '*.css' under directory 'doc'
2014-02-03 11:09:07.516 | 2014-02-03 11:09:07 warning: no files found matching '*.js' under directory 'doc'
2014-02-03 11:09:07.516 | 2014-02-03 11:09:07 warning: no files found matching '*.html' under directory 'doc'
2014-02-03 11:09:07.517 | 2014-02-03 11:09:07 warning: no files found matching '*.conf' under directory 'doc'
2014-02-03 11:09:07.517 | 2014-02-03 11:09:07 warning: no files found matching '*.jpg' under directory 'doc'
2014-02-03 11:09:07.517 | 2014-02-03 11:09:07 warning: no files found matching '*.gif' under directory 'doc'
2014-02-03 11:09:07.518 | 2014-02-03 11:09:07 warning: no files found matching '*.png' under directory 'doc'
2014-02-03 11:09:07.518 | 2014-02-03 11:09:07 warning: no files found matching '*.css_t' under directory 'doc'
2014-02-03 11:09:07.518 | 2014-02-03 11:09:07 warning: no files found matching '*.csv' under directory 'horizon'
2014-02-03 11:09:07.519 | 2014-02-03 11:09:07 warning: no files found matching '*.template' under directory 'horizon'
2014-02-03 11:09:07.519 | 2014-02-03 11:09:07 warning: no files found matching '*.js' under directory 'openstack_dashboard'
2014-02-03 11:09:07.519 | 2014-02-03 11:09:07 warning: no files found matching 'AUTHORS'
2014-02-03 11:09:07.520 | 2014-02-03 11:09:07 warning: no files found matching 'ChangeLog'
2014-02-03 11:09:07.520 | 2014-02-03 11:09:07 warning: no files found matching 'doc/source/_templates/.placeholder'
2014-02-03 11:09:07.520 | 2014-02-03 11:09:07 warning: no previously-included files found matching 'openstack_dashboard/local/local_settings.py'
2014-02-03 11:09:07.521 | 2014-02-03 11:09:07 Requirement already satisfied (use --upgrade to upgrade): pbr>=0.5.21,<1.0 in /opt/stack/new/pbr (from horizon==2014.1.dev47.gc1fbaa8)
2014-02-03 11:09:07.521 | 2014-02-03 11:09:07 Downloading/unpacking Django>=1.4,<1.6 (from horizon==2014.1.dev47.gc1fbaa8)
2014-02-03 11:09:07.521 | 2014-02-03 11:09:07 Error <urlopen error [Errno 101] Network is unreachable> while getting http://pypi.openstack.org/openstack/Django/Django-1.5.5.tar.gz (from http://pypi.openstack.org/openstack/Django/)
2014-02-03 11:09:07.522 | 2014-02-03 11:09:07 Cleaning up...
2014-02-03 11:09:07.522 | 2014-02-03 11:09:07 Exception:
2014-02-03 11:09:07.522 | 2014-02-03 11:09:07 Traceback (most recent call last):
2014-02-03 11:09:07.551 | 2014-02-03 11:09:07 File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/basecommand.py", line 134, in main
2014-02-03 11:09:07.551 | 2014-02-03 11:09:07 status = self.run(options, args)
2014-02-03 11:09:07.804 | 2014-02-03 11:09:07 File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/commands/install.py", line 236, in run
2014-02-03 11:09:07.806 | 2014-02-03 11:09:07 requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
2014-02-03 11:09:07.808 | 2014-02-03 11:09:07 File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/req.py", line 1092, in prepare_files
2014-02-03 11:09:07.809 | 2014-02-03 11:09:07 self.unpack_url(url, location, self.is_download)
2014-02-03 11:09:07.811 | 2014-02-03 11:09:07 File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/req.py", line 1238, in unpack_url
2014-02-03 11:09:07.847 | 2014-02-03 11:09:07 retval = unpack_http_url(link, location, self.download_cache, self.download_dir)
2014-02-03 11:09:07.848 | 2014-02-03 11:09:07 File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/download.py", line 602, in unpack_http_url
2014-02-03 11:09:07.849 | 2014-02-03 11:09:07 resp = _get_response_from_url(target_url, link)
2014-02-03 11:09:07.849 | 2014-02-03 11:09:07 File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/download.py", line 638, in _get_response_from_url
2014-02-03 11:09:07.849 | 2014-02-03 11:09:07 resp = urlopen(target_url)
2014-02-03 11:09:07.850 | 2014-02-03 11:09:07 File "/usr/local/lib/python2.7/dist-packages/pip-1.4.1-py2.7.egg/pip/download.py", line 176, in __call__
2014-02-03 11:09:07.850 | 2014-02-03 11:09:07 response = self.get_opener(scheme=scheme).open(url)
2014-02-03 11:09:07.851 | 2014-02-03 11:09:07 File "/usr/lib/python2.7/urllib2.py", line 400, in open
2014-02-03 11:09:07.851 | 2014-02-03 11:09:07 response = self._open(req, data)
2014-02-03 11:09:07.852 | 2014-02-03 11:09:07 File "/usr/lib/python2.7/urllib2.py", line 418, in _open
2014-02-03 11:09:07.852 | 2014-02-03 11:09:07 '_open', req)
2014-02-03 11:09:07.853 | 2014-02-03 11:09:07 File "/usr/lib/python2.7/urllib2.py", line 378, in _call_chain
2014-02-03 11:09:07.853 | 2014-02-03 11:09:07 result = func(*args)
2014-02-03 11:09:07.853 | 2014-02-03 11:09:07 File "/usr/lib/python2.7/urllib2.py", line 1207, in http_open
2014-02-03 11:09:07.854 | 2014-02-03 11:09:07 return self.do_open(httplib.HTTPConnection, req)
2014-02-03 11:09:07.854 | 2014-02-03 11:09:07 File "/usr/lib/python2.7/urllib2.py", line 1177, in do_open
2014-02-03 11:09:07.854 | 2014-02-03 11:09:07 raise URLError(err)
2014-02-03 11:09:07.855 | 2014-02-03 11:09:07 URLError: <urlopen error [Errno 101] Network is unreachable>

Bug 1266616 appears to be a subset of these failures.