On Wed, Nov 09, 2016 at 02:54:59PM -0800, Mike Dacre wrote: > I have no idea how to debug this. As of git version 2.10.0 git hangs > indefinitely when I run `git mergetool`, the result is the same if I > run `git mergetool --tool-help`. Mergetool is a shell script. Try setting GIT_TRACE=1 in the environment to see which git programs it's running. Of course it may be hanging in a non-git program, too. Try: PATH=$(git --exec-path):$PATH sh -x $(which git-mergetool) --tool-help to get a dump from the shell. > I am on Arch Linux, with all of my software updated to the latest > versions as of this morning. git 2.9.3 and lower works perfectly. > > Any ideas? If it works on v2.9.3 and the bug reproduces, you should be able to use "git bisect" to find the commit that introduces the problem. There weren't a lot of changes to the shell scripts in that time frame, so just as a guess, it may be related to d323c6b64 (i18n: git-sh-setup.sh: mark strings for translation, 2016-06-17), which was the only significant change in that time. -Peff