Merge branch 'ab/hook-api-with-stdin'

Extend the run-hooks API to allow feeding data from the standard
input when running the hook script(s).

* ab/hook-api-with-stdin:
  hook: support a --to-stdin=<path> option
  sequencer: use the new hook API for the simpler "post-rewrite" call
  hook API: support passing stdin to hooks, convert am's 'post-rewrite'
  run-command: allow stdin for run_processes_parallel
  run-command.c: remove dead assignment in while-loop

builtin/am.c

@@ -495,24 +495,12 @@ static int run_applypatch_msg_hook(struct am_state *state)
  */
 static int run_post_rewrite_hook(const struct am_state *state)
 {
-	struct child_process cp = CHILD_PROCESS_INIT;
-	const char *hook = find_hook("post-rewrite");
-	int ret;
+	struct run_hooks_opt opt = RUN_HOOKS_OPT_INIT;
 
-	if (!hook)
-		return 0;
+	strvec_push(&opt.args, "rebase");
+	opt.path_to_stdin = am_path(state, "rewritten");
 
-	strvec_push(&cp.args, hook);
-	strvec_push(&cp.args, "rebase");
-
-	cp.in = xopen(am_path(state, "rewritten"), O_RDONLY);
-	cp.stdout_to_stderr = 1;
-	cp.trace2_hook_name = "post-rewrite";
-
-	ret = run_command(&cp);
-
-	close(cp.in);
-	return ret;
+	return run_hooks_opt("post-rewrite", &opt);
 }
 
 /**