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

commit.h

@@ -304,4 +304,7 @@ extern void check_commit_signature(const struct commit* commit, struct signature
 
 int compare_commits_by_commit_date(const void *a_, const void *b_, void *unused);
 
+LAST_ARG_MUST_BE_NULL
+extern int run_commit_hook(int editor_is_used, const char *index_file, const char *name, ...);
+
 #endif /* COMMIT_H */