BUG#37631 - Incorrect key file for table after upgrading from 5.0 to 5.1

This patch adds corrections to the original patch
submitted 2009-04-08 (http://lists.mysql.com/commits/71607):

- fixed that the original patch didn't work because of an
  incorrect condition;
- added a test case.

mysql-test/r/upgrade.result:
  Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
  
  Result file for test case
mysql-test/std_data/bug37631.MYD:
  Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
  
  table created in mysql 4.0
mysql-test/std_data/bug37631.MYI:
  Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
  
  table created in mysql 4.0
mysql-test/std_data/bug37631.frm:
  Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
  
  table created in mysql 4.0
mysql-test/t/upgrade.test:
  Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
  
  Adds test for checking that upgrade works
  on a table which is created by a mysql
  server version <= 4.0.
storage/myisam/ha_myisam.cc:
  Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
  
  Fix the conformance checker to relax checking
  for the correct version of the tables (for tables
  created by mysql server version <= 4.0)

mysql-test/r/upgrade.result

@@ -57,6 +57,18 @@ s1
 1
 drop table `txu@0023p@0023p1`;
 drop table `txu#p#p1`;
+#
+# Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
+#
+# copy table created using mysql4.0 into the data dir
+# check the table created using mysql 4.0
+CHECK TABLE t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	error	Table upgrade required. Please do "REPAIR TABLE `t1`" or dump/reload to fix it!
+# query the table created using mysql 4.0
+SELECT * FROM t1;
+c1	c2	c3
+DROP TABLE t1;
 truncate t1;
 drop table t1;
 drop database if exists `tabc`;

mysql-test/t/upgrade.test

@@ -48,6 +48,20 @@ select * from `txu#p#p1`;
 drop table `txu@0023p@0023p1`;
 drop table `txu#p#p1`;
 
+--echo #
+--echo # Bug#37631 Incorrect key file for table after upgrading from 5.0 to 5.1
+--echo #
+--echo # copy table created using mysql4.0 into the data dir
+let $MYSQLD_DATADIR= `SELECT @@datadir`;
+copy_file std_data/bug37631.frm $MYSQLD_DATADIR/test/t1.frm;
+copy_file std_data/bug37631.MYD $MYSQLD_DATADIR/test/t1.MYD;
+copy_file std_data/bug37631.MYI $MYSQLD_DATADIR/test/t1.MYI;
+--echo # check the table created using mysql 4.0
+CHECK TABLE t1;
+--echo # query the table created using mysql 4.0
+SELECT * FROM t1;
+DROP TABLE t1;
+
 #
 # Check if old tables work
 #

storage/myisam/ha_myisam.cc

@@ -392,7 +392,7 @@ int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
                             test(t2_keyinfo[i].flag & HA_SPATIAL)));
        DBUG_RETURN(1);
     }
-    if ((mysql_40_compat &&
+    if ((!mysql_40_compat &&
         t1_keyinfo[i].key_alg != t2_keyinfo[i].key_alg) ||
         t1_keyinfo[i].keysegs != t2_keyinfo[i].keysegs)
     {
@@ -424,7 +424,7 @@ int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
           t1_keysegs_j__type= HA_KEYTYPE_VARBINARY1; /* purecov: inspected */
       }
 
-      if ((mysql_40_compat &&
+      if ((!mysql_40_compat &&
           t1_keysegs[j].language != t2_keysegs[j].language) ||
           t1_keysegs_j__type != t2_keysegs[j].type ||
           t1_keysegs[j].null_bit != t2_keysegs[j].null_bit ||