Bug 411544: Subject lines were still being improperly line-broken in emails.

Bugzilla/Mailer.pm

@@ -44,6 +44,7 @@ use Bugzilla::Util;
 use Date::Format qw(time2str);
 
 use Encode qw(encode);
+use Encode::MIME::Header;
 use Email::Address;
 use Email::MIME;
 # Loading this gives us encoding_set.
@@ -78,9 +79,11 @@ sub MessageToMTA {
             if (Bugzilla->params->{'utf8'} && !utf8::is_utf8($value)) {
                 utf8::decode($value);
             }
+
+            # avoid excessive line wrapping done by Encode.
+            local $Encode::Encoding{'MIME-Q'}->{'bpl'} = 998;
+
             my $encoded = encode('MIME-Q', $value);
-            # Encode adds unnecessary line breaks, with two spaces after each.
-            $encoded =~ s/\n  / /g;
             $email->header_set($header, $encoded);
         }
     }