sagemath/git-trac-command — pull request #7 by nesciens (2014-05-02 14:11:13+00:00)
Title: Use git's pushURL (requires git >= 1.6.4)

This way the readonly option is no longer required.

Fetching always happens through the anonymous git://-url. Pushing requires ssh.

Since Debian squeeze has git 1.7.2 and Ubuntu lucid has git 1.7.0, I think
git>=1.6.4 should be fine.