d6e7e20123
If you call :Gdiff on a file that's also open in a separate tab, close it, switch to another file, and call :Gdiff again, Vim thinks the first file is part of a 3-way diff, despite no longer being displayed in a window. Curiously, :diffoff! seems to work around this, despite both the documentation and source code suggesting it merely iterates over open windows. Closes https://github.com/tpope/vim-fugitive/issues/534