In MIME encoder, put a check at the end of the loop if the source points to a null character then bump the

pointer. This fixes a problem when a separator is at the end of a header string. Bug 9762, r=cata.

mailnews/mime/src/comi18n.cpp

@@ -948,6 +948,8 @@ convert_and_encode:
     if (end == NULL)
       break;
     begin = end + 1;
+    if ('\0' == *begin)
+      begin++;
   }
 
   if (srcbuf)