Merge branch 'cc/run-command'

* cc/run-command:
  run-command: Redirect stderr to a pipe before redirecting stdout to stderr

Documentation/technical/api-run-command.txt

@@ -111,9 +111,10 @@ stderr as follows:
 	.no_stdin, .no_stdout, .no_stderr: The respective channel is
 		redirected to /dev/null.
 
-	.stdout_to_stderr: stdout of the child is redirected to the
-		parent's stderr (i.e. *not* to what .err or
-		.no_stderr specify).
+	.stdout_to_stderr: stdout of the child is redirected to its
+		stderr. This happens after stderr is itself redirected.
+		So stdout will follow stderr to wherever it is
+		redirected.
 
 To modify the environment of the sub-process, specify an array of
 string pointers (NULL terminated) in .env:

run-command.c

@@ -91,6 +91,13 @@ int start_command(struct child_process *cmd)
 			close(cmd->in);
 		}
 
+		if (cmd->no_stderr)
+			dup_devnull(2);
+		else if (need_err) {
+			dup2(fderr[1], 2);
+			close_pair(fderr);
+		}
+
 		if (cmd->no_stdout)
 			dup_devnull(1);
 		else if (cmd->stdout_to_stderr)
@@ -103,13 +110,6 @@ int start_command(struct child_process *cmd)
 			close(cmd->out);
 		}
 
-		if (cmd->no_stderr)
-			dup_devnull(2);
-		else if (need_err) {
-			dup2(fderr[1], 2);
-			close_pair(fderr);
-		}
-
 		if (cmd->dir && chdir(cmd->dir))
 			die("exec %s: cd to %s failed (%s)", cmd->argv[0],
 			    cmd->dir, strerror(errno));