tpope/vim-git — pull request #7 by agscala (2012-03-06 16:42:07+00:00)
Title: `--no-ext-diff` on git diffs

diffs aren't presented correctly unless `--no-ext-diff` is on under some circumstances.

In my situation, I set up git diff to run vimdiff on the two files. Then, I set up my .vimrc to show me the diff during a git commit like this: http://vimbits.com/bits/173

The diff wasn't displayed correctly because it was trying to run vimdiff instead of just printing the standard git diff.