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

diff --cc git-send-email.perl
index dd7560b180adcba90a1fc3dc94c206b567398e9e,195fe6f70a3a13c17b67ad8d067e8e0ff4cc9195..d8319d45fb275c783511232c7b0047a517973e03
--- 1/git-send-email.perl
--- 2/git-send-email.perl
+++ b/git-send-email.perl
@@@ -361,10 -317,14 +361,11 @@@ if ($thread && !defined $initial_reply_
        } while (!defined $_);
  
        $initial_reply_to = $_;
-       $initial_reply_to =~ s/(^\s+|\s+$)//g;
+       $initial_reply_to =~ s/^\s+<?/</;
+       $initial_reply_to =~ s/>?\s+$/>/;
  }
  
 -if (!$smtp_server) {
 -      $smtp_server = $repo->config('sendemail.smtpserver');
 -}
 -if (!$smtp_server) {
 +if (!defined $smtp_server) {
        foreach (qw( /usr/sbin/sendmail /usr/lib/sendmail )) {
                if (-x $_) {
                        $smtp_server = $_;