subrepo: speed up git push logic In many common cases where the subrepo is up to date with the remote repo, hg push will only need to run one git-branch command to see that nothing needs to be pushed.

subrepo: use subprocess.Popen without the shell As well as simplifying the code, this makes subprocess calls about 25% faster. Tested on a couple linux boxes. python -mtimeit -s'import subprocess' 'subprocess.Popen( "git version", shell=True, stdout=subprocess.PIPE).wait()' python -mtimeit -s'import subprocess' 'subprocess.Popen( ["git","version"], stdout=subprocess.PIPE).wait()'