Merge branch 'maint'

* maint:
  stash: end index commit log with a newline
  git-commit: Disallow amend if it is going to produce an empty non-merge commit
  git-send-email.perl: Add angle brackets to In-Reply-To if necessary
  Fix a test failure (t9500-*.sh) on cygwin

git-send-email.perl

@@ -361,7 +361,8 @@ if ($thread && !defined $initial_reply_to && $prompting) {
 	} while (!defined $_);
 
 	$initial_reply_to = $_;
-	$initial_reply_to =~ s/(^\s+|\s+$)//g;
+	$initial_reply_to =~ s/^\s+<?/</;
+	$initial_reply_to =~ s/>?\s+$/>/;
 }
 
 if (!defined $smtp_server) {