Revert 30816237 and 7e62265

It seems that we have bad interaction with the code related to
GIT_WORK_TREE and "grep --no-index", and broke running grep inside
the .git directory.  For now, just revert it and resurrect it after
1.7.0 ships.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

git.c

@@ -317,7 +317,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "fsck-objects", cmd_fsck, RUN_SETUP },
 		{ "gc", cmd_gc, RUN_SETUP },
 		{ "get-tar-commit-id", cmd_get_tar_commit_id },
-		{ "grep", cmd_grep, USE_PAGER },
+		{ "grep", cmd_grep, RUN_SETUP | USE_PAGER },
 		{ "hash-object", cmd_hash_object },
 		{ "help", cmd_help },
 		{ "index-pack", cmd_index_pack },