Python system apps must hardcode system python in #! line

[Barry Warsaw]

I just attempted an upgrade from feisty to gutsy, but this upgrade eventually failed with an import error:

Setting up gnome-app-install (0.4.8-0ubuntu1) ...
Traceback (most recent call last):
  File "/usr/sbin/update-app-install", line 3, in <module>
    from AppInstall.update import main
ImportError: No module named AppInstall.update
dpkg: error processing gnome-app-install (--configure):
 subprocess post-installation script returned error exit status 1

It strikes me that I've seen this probably before with incorrectly written system applications. See for example this bug:

https://bugs.launchpad.net/bzr/+bug/134046

The problem will often hit Python developers such as myself. While it is generally correct to recommend that the #! line for development packages be

#! /usr/bin/env python

it is actually /incorrect/ to use this line in system tools because if I have a development Python in my $PATH, the tool will break. The expected packages won't be present in my dev Python's site-packages.

In fact, Python's own distutils/setuptools package manager hardcodes the #! line to the version of Python you use to install the package, even if the original script has /usr/bin/env in it. This is always the correct thing to do.

In short: system tools /must always/ use the system python.

[Jean-Baptiste Lallement (jibel)]

Fixed in 0.4.10-0ubuntu1