BUG#32050 - table logging gone wrong.

INSERT/UPDATE against CSV table created by MySQL earlier than 5.1.23
with NULL-able column results in server crash in debug builds.

Starting with 5.1.23 CSV doesn't permit creation of NULL-able columns,
but it is still possible to get such table from older MySQL versions.

Fixed by removing excessive DBUG_ASSERT().

scripts/mysql_system_tables_fix.sql

@@ -513,6 +513,22 @@ ALTER TABLE tables_priv MODIFY Table_priv set('Select','Insert','Update','Delete
 
 UPDATE user SET Trigger_priv=Super_priv WHERE @hadTriggerPriv = 0;
 
+#
+# Log Table
+#
+
+ALTER TABLE general_log 
+  MODIFY COLUMN user_host MEDIUMTEXT NOT NULL,
+  MODIFY COLUMN thread_id INTEGER NOT NULL,
+  MODIFY COLUMN server_id INTEGER NOT NULL,
+  MODIFY COLUMN command_type VARCHAR(64) NOT NULL,
+  MODIFY COLUMN argument MEDIUMTEXT NOT NULL;
+ALTER TABLE slow_log
+  MODIFY COLUMN db VARCHAR(512) NOT NULL,
+  MODIFY COLUMN last_insert_id INTEGER NOT NULL,
+  MODIFY COLUMN insert_id INTEGER NOT NULL,
+  MODIFY COLUMN server_id INTEGER NOT NULL;
+
 # Activate the new, possible modified privilege tables
 # This should not be needed, but gives us some extra testing that the above
 # changes was correct

storage/csv/ha_tina.cc

@@ -472,14 +472,6 @@ int ha_tina::encode_quote(uchar *buf)
     const char *ptr;
     const char *end_ptr;
     const bool was_null= (*field)->is_null();
-
-    /*
-      CSV does not support nulls. ::create() prevents creation of a table
-      with nullable columns so if we encounter them here, there is a bug.
-      This may only occur if the frm was created by an older version of
-      mysqld which permitted table creation with nullable columns.
-    */
-    DBUG_ASSERT(!(*field)->maybe_null());
     
     /*
       assistance for backwards compatibility in production builds.