add the python-distutils-extra dependancy

[bzg]

I tried to do a fresh sugar-jhbuild install.
I pulled the repo and updated it without trouble.

./sugar-jhbuild depscheck told me to install python-empy

Then ./sugar-jhbuild:

,----
| * Checking out sugar-update-control * [25/40]
| git pull --rebase
| Current branch master is up to date.
| * Building sugar-update-control * [25/40]
| python setup.py build
| Traceback (most recent call last):
| File "setup.py", line 2, in <module>
| from DistUtilsExtra.command import * # gettext support
| ImportError: No module named DistUtilsExtra.command
`----

sudo apt-get install python-distutils-extra solves this problem.

It should be added to the list of dependencies.

[sascha_silbe]

Fixed on all distros (package name for Mandriva is just a guess, though), thanks for the report!