Parameter to specify version system

[lapo-luchini]

I have some cross-versioning system projects, e.g. with both a local .git and a .svn in some upper directory.
Right now I usually temporarily rename .git to .git2 or something when I want to commit to SVN, but it could make sense a parameter like commit-partial --svn to force searching only for that.
(same goes for being capable to commit into git when .svn is at the same level)