"Variable referenced before initialization" using Cython 0.15 to compile extensions

Apparently quite a few people are now running into this in the form of errors like:

Traceback (most recent call last):
   ...
   File "_dirstate_helpers_pyx.pyx", line 1459, in bzrlib._dirstate_helpers_pyx.ProcessEntryC.__next__ (bzrlib/_dirstate_helpers_pyx.c:12037)
   File "_dirstate_helpers_pyx.pyx", line 1732, in bzrlib._dirstate_helpers_pyx.ProcessEntryC._iter_next (bzrlib/_dirstate_helpers_pyx.c:14786)
   File "_dirstate_helpers_pyx.pyx", line 1888, in bzrlib._dirstate_helpers_pyx.ProcessEntryC._loop_one_block (bzrlib/_dirstate_helpers_pyx.c:16487)
 UnboundLocalError: local variable 'changed' referenced before assignment

Status changed to 'Confirmed' because the bug affects multiple users.

Please update bzr in precise first, as per SRU policy. Otherwise this can't progress into -updates.

Hello John, or anyone else affected,

Accepted bzr into oneiric-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

This bug was fixed in the package bzr - 2.5.0~beta2-0ubuntu1

---------------
bzr (2.5.0~beta2-0ubuntu1) precise; urgency=low

  * New upstream release.
   + Fixes compatibility with cython 0.15. LP: #837221
   + Fixes handling of timestamps in diffs for absent files in working tree.
     LP: #847435
   + Fixes overflow error in dirstate when dealing with large files.
     LP: #683191
  * Merge from Debian. Remaining changes:
   + Drop build dependencies on python-{subunit,meliae,lzma,medusa}, which are
     not in main.
   + Disable support for running selftest in parallel (requires subunit).
 -- Jelmer Vernooij <email address hidden> Fri, 04 Nov 2011 22:55:11 +0100

The fix for this bug has been awaiting testing feedback in the -proposed repository for oneiric for more than 90 days. Please test this fix and update the bug appropriately with the results. In the event that the fix for this bug is still not verified 15 days from now, the package will be removed from the -proposed repository.

Ran an oneiric instance using the following image:

 smoser-cloud-images/ubuntu-oneiric-11.10-amd64-server-20120722

Upgraded bzr and related packaged to 2.4.2 from the -proposed archive:

 Commandline: apt-get upgrade bzr
 Upgrade: byobu:amd64 (4.37-0ubuntu1, 4.37-0ubuntu1.1), unattended-upgrades:amd64 (0.73ubuntu1, 0.73ubuntu1.1), python-bzrlib.tests:amd64 (2.4.1-1ubuntu1, 2.4.2-0ubuntu1), procps:amd64 (3.2.8-10ubuntu5, 3.2.8-10ubuntu5.1), python-bzrlib:amd64 (2.4.1-1ubuntu1, 2.4.2-0ubuntu1), bzr:amd64 (2.4.1-1ubuntu1, 2.4.2-0ubuntu1), libgcrypt11:amd64 (1.5.0-1, 1.5.0-1ubuntu0.1)

To verify that the upgrade from 2.4.1 to 2.4.2 worked as expected, ran the test suite:

 ubuntu@test:~$ bzr selftest
 bzr selftest: /usr/bin/bzr
    /usr/lib/python2.7/dist-packages/bzrlib
    bzr-2.4.2 python-2.7.2 Linux-3.0.0-23-virtual-x86_64-with-Ubuntu-11.10-oneiric
 ...
 ----------------------------------------------------------------------
 Ran 26912 tests in 1392.984s

 FAILED (failures=1, known_failure_count=34)
 1299 tests skipped

The test failure is some minor apport/vm weirdness in bt.test_crash that also failed prior to the package upgrade.

The verification of this Stable Release Update has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regresssions.

This bug was fixed in the package bzr - 2.4.2-0ubuntu1

---------------
bzr (2.4.2-0ubuntu1) oneiric-proposed; urgency=low

  * New upstream release.
   + Fix OverflowError in _dirstate_helpers_pyx.c. LP: #683191
   + Fix compatibility with Cython 0.15. LP: #837221
 -- Jelmer Vernooij <email address hidden> Wed, 02 Nov 2011 15:01:08 +0100