"git grep --no-index" should not get affected by the contents of
the .gitmodules file but when "--recurse-submodules" is given or
the "submodule.recurse" variable is set, it did. Now these
settings are ignored in the "--no-index" mode.
* pb/do-not-recurse-grep-no-index:
grep: ignore --recurse-submodules if --no-index is given