In CVS, we could programatically create a new branch of existing source using the "rtag" command, which did not require a copy of the repository. Does git support functionality of this kind, making a branch of existing files in a remote git repository without having a local copy of it? Or does the distributed nature of git preclude this? (I'm trying to save the 20+ minutes it would take to make a freestanding copy of the repository, just to run a 'git branch' command.)