Git for Windows uses MSYS, which is actually a fork of Cygwin. Compared to Cygwin, Git's MSYS distro is missing a lot of software and the version of Vim packaged with Git for Windows is a native Windows build (not MSYS-aware,) so it doesn't work in mintty. This can really bite you when editing a commit message or trying to do an interactive rebase. On my machine, Vim will just hang when started from an MSYS mintty.