If a commit contains a .patch, the parsing logic for https://github.com/schacon/ruby-git/blob/master/lib/git/diff.rb#L132 fails. It'll start reporting, for example: type: '-deleted'. The patch in a diff will be printed out as -deleted file mode 100644.

To reproduce, try committing https://github.com/isaacs/readable-stream/blob/master/float.patch and do repo.diff(prev_commit, head_commit)