send-email: fix uninitialized var warning for $smtp_auth

On the latest version of git-send-email, I see this error just before
running SMTP auth (I didn't provide any --smtp-auth= parameter):

  Use of uninitialized value $smtp_auth in pattern match (m//) at \
  /home/briannorris/git/git/git-send-email.perl line 1139.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-send-email.perl b/git-send-email.perl
index 6e380a25be9e49f97644f6a8d9f835f9e42a628a..cfe26e5029f6376585d8e60f8886de1840d35200 100755 (executable)
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -1142,7 +1142,7 @@ sub smtp_auth_maybe {
 
        # Check mechanism naming as defined in:
        # https://tools.ietf.org/html/rfc4422#page-8
-       if ($smtp_auth !~ /^(\b[A-Z0-9-_]{1,20}\s*)*$/) {
+       if ($smtp_auth && $smtp_auth !~ /^(\b[A-Z0-9-_]{1,20}\s*)*$/) {
                die "invalid smtp auth: '${smtp_auth}'";
        }