Fixed bug where CHECK TABLE for a MYISAM table before 5.5.38 wrongly gave warning:

"Table upgrade required..."

The row format is only different for the case where we have a very old MyISAM table with varchar fields, null fields and created with CHECKSUM=1
The table is usable, except that CHECKSUM TABLE will give a wrong result and CHECK TABLE will warn about this.

I added a test for this to warn when a table needs to be upgraded, but forgot to add a test that this was only relevant for tables with CHECKSUM=1
This is now fixed.



storage/myisam/ha_myisam.cc:
  Fixed wrong test.

storage/myisam/ha_myisam.cc

@@ -2160,7 +2160,8 @@ bool ha_myisam::check_if_incompatible_data(HA_CREATE_INFO *info,
 
 int ha_myisam::check_for_upgrade(HA_CHECK_OPT *check_opt)
 {
-  if (!(file->s->options & HA_OPTION_NULL_FIELDS) &&
+  if ((file->s->options & HA_OPTION_CHECKSUM) &&
+      !(file->s->options & HA_OPTION_NULL_FIELDS) &&
       !(file->s->options & HA_OPTION_PACK_RECORD) &&
       file->s->has_varchar_fields)
   {