This fixes issue 394 from msysgit. It seems that the Gnuwin32 project
provides a nice command but it returns a "not implemented" error. To
help users we now try to execute once and disable it in case it fails.
Signed-off-by: NHeiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>