Merge branch 'da/rev-parse-verify-quiet'

"rev-parse --verify --quiet $name" is meant to quietly exit with a non-zero status when $name is not a valid object name, but still gave error messages in some cases. * da/rev-parse-verify-quiet: stash: prefer --quiet over shell redirection of the standard error stream refs: make rev-parse --quiet actually quiet t1503: use test_must_be_empty Documentation: a note about stdout for git rev-parse --verify --quiet