[Bug 1830635] Re: Regression: xenial: Uses apt_pkg.Error, which is only available in later versions

[Łukasz Zemczak]

Hello Julian, or anyone else affected,

Accepted python-apt into xenial-proposed. The package will build now and
be available at https://launchpad.net/ubuntu/+source/python-
apt/1.1.0~beta1ubuntu0.16.04.5 in a few hours, and then in the -proposed
repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-xenial to verification-done-xenial. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-xenial. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: python-apt (Ubuntu Xenial)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-xenial

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https://bugs.launchpad.net/bugs/1830635

Title:
  Regression: xenial: Uses apt_pkg.Error, which is only available in
  later versions

Status in python-apt package in Ubuntu:
  Invalid
Status in python-apt source package in Xenial:
  Fix Committed

Bug description:
  [Impact]
  The last SRU introduced a regression in error handling, where apt_pkg.Error is being caught - but that class is not available in xenial - it still uses SystemError

  [Test case]

  Run python3 -c "import apt; apt.Cache().update()" while running apt
  update.

  You should see:

  # <command>
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/usr/lib/python2.7/dist-packages/apt/cache.py", line 468, in update
      raise LockFailedException("Failed to lock %s" % lockfile)
  apt.cache.LockFailedException: Failed to lock /var/lib/apt/lists/lock

  Currently you see:
  # <command>
  Traceback (most recent call last):
    File "/usr/lib/python3/dist-packages/apt/cache.py", line 63, in __enter__
      return self._lock.__enter__()
  SystemError: E:Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable)

  During handling of the above exception, another exception occurred:

  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/usr/lib/python3/dist-packages/apt/cache.py", line 481, in update
      with _WrappedLock(apt_pkg.config.find_dir("Dir::State::Lists")):
    File "/usr/lib/python3/dist-packages/apt/cache.py", line 64, in __enter__
      except apt_pkg.Error as e:
  AttributeError: module 'apt_pkg' has no attribute 'Error'

  [Regression potential]
  It really can't get worse than this. But FWIW: This only affects code paths where we could not lock the lists/ or archives/ directory - they currently throw the AttributeError, and will then throw LockFailedException again - as they did before the SRU.

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