Fix displaying of multipart/alternative messages with empty parts (#1488750)

Conflicts:

	CHANGELOG

CHANGELOG

@@ -1,6 +1,7 @@
 CHANGELOG Roundcube Webmail
 ===========================
 
+- Fix displaying of multipart/alternative messages with empty parts (#1488750)
 - Fix Warning: htmlspecialchars(): charset `RCMAIL_CHARSET' not supported warning in Installer (#1488744)
 - Fix threaded list sorting on PHP < 5.2.9 (#1488748)
 

program/include/rcube_message.php

@@ -364,6 +364,10 @@ class rcube_message
             foreach ($structure->parts as $p => $sub_part) {
                 $sub_mimetype = $sub_part->mimetype;
 
+                // skip empty parts
+                if (!$sub_part->size)
+                    continue;
+
                 // check if sub part is
                 if ($sub_mimetype == 'text/plain')
                     $plain_part = $p;