3ab50376b0
When `hermes update` stashes local changes and the subsequent `git stash apply` fails or leaves unmerged files, the conflict markers (<<<<<<< etc.) were left in the working tree, making Hermes unrunnable until manually cleaned up. Now the update command runs `git reset --hard HEAD` to restore a clean working tree before exiting, and also detects unmerged files even when git stash apply reports success. Closes #2348