One question, because you seem to know Git better than I do:
Do you know since which version Git supports
refs/heads/*:refs/heads/* and refs/tags/*:refs/tags/* ?
I'd like to put some kind of system requirements into the readme, e.g. the minimal Git version that you need for using Bitbucket Backup.
I only know that it works with 1.7.7 because I have that one on my machine and your changes work here, and I already wrote in the issue that refs/heads/*:refs/heads/* didn't work on my other machine with 188.8.131.52.
If not, I'll just leave 1.7.7 in the readme.
Sorry, replied to you as a message instead of here.
Quick recap: I doubt anyone will be using anything older than 1.7, and I don't recall exactly but I'm sure it's a 1.7 feature so putting >= 1.7.x in the requirements will probably be sufficient.
Worst case scenario, someone reports that it doesn't work. We can always add code later on to parse the git version and use a different command.