Merge branch 'bp/commit-p-editor' into maint

* bp/commit-p-editor: run-command: mark run_hook_with_custom_index as deprecated merge hook tests: fix and update tests merge: fix GIT_EDITOR override for commit hook commit: fix patch hunk editing with "commit -p -m" test patch hunk editing with "commit -p -m" merge hook tests: use 'test_must_fail' instead of '!' merge hook tests: fix missing '&&' in test