See http://www.python.org/dev/buildbot/all/builders/x86%20XP-5%203.x/builds/104/steps/test/logs/stdio for the failure, but basically:

======================================================================
ERROR: test_UNC_path (test.test_import.PathsTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\Buildslave\3.x.moore-windows\build\lib\test\test_import.py", line 469, in _test_UNC_path
    mod = __import__("test_trailing_slash")
  File "<frozen importlib._bootstrap>", line 1003, in _find_and_load
ImportError: No module named 'test_trailing_slash'

----------------------------------------------------------------------


It seems spontaneous as the test succeeded previously and the commit it failed on didn't even touch code compiled by Windows.

I think that the line just before the __import__ call:

sys.path.append(path)

should say

sys.path.append(unc)

With this change, test_import passes for me (on the pythonv branch).

New changeset 0356103cde28 by Brett Cannon in branch 'default':
Issue #14637: Fix the UNC import test under Windows to actually use
http://hg.python.org/cpython/rev/0356103cde28

Thanks for catching that, Vinay! Just waiting for the buildbots to verify my fix (which also included invalidating the cache which is why it was sporadic plus cleaning up sys.path properly).

Thanks for catching that, Vinay! Buildbots say it worked.