Merge branch 'pb/do-not-recurse-grep-no-index' into maint

"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