changegroup: pass 'repo' to allsupportedversions
In the next changesets, we will introduce more logic directly related to the
repository to decide what version have to be supported. So we now directly pass
the repo object instead of just ui.
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.