Fix bug: pass commit as hash string, not object

[mikkoi]

Git::Repository::run() does not interpret Git::Repository::Log objects into strings (commit hash string). We need to do this when we pass commits to Git command line.

Signed-off-by: Mikko Johannes Koivunalho mikko.koivunalho@iki.fi

[gnustavo]

Thank you, Mikko.