grep: die gracefully when outside repository
Die gracefully when `git grep --no-index` is run outside of a Git repository and the path is outside the directory tree. If you are not in a Git repository and say: git grep --no-index search .. You trigger a `BUG`: BUG: environment.c:213: git environment hasn't been setup Aborted (core dumped) Because `..` is a valid path which is treated as a pathspec. Then `pathspec` figures out that it is not in the current directory tree. The `BUG` is triggered when `pathspec` tries to advise the user about how the path is not in the current (non-existing) repository. Reported-by: ks1322 ks1322 <ks1322@gmail.com> Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name> Signed-off-by: Junio C Hamano <gitster@pobox.com>