Hi, While trying to use `git fmt-merge-msg`, I figured it only accepts inputs in the format used in the 'FETCH_HEAD' file. I then tried to find a description of the format of this file in the documentation, but could not find any. For example, 'git grep not-for-merge' in /Documentation returns a single hit, in the release notes for Git 2.5.0. I think it could be good if we documented the FETCH_HEAD format. Cheers, Philippe.
