sqldiff strips auto_increment from bigint primary keys

[GoogleCodeExporter]

We use BigAutoField as our primary key ids from here: 
http://www.djangosnippets.org/snippets/1244/

When using sqldiff, it suggests:

ALTER TABLE <table> MODIFY `id` bigint;

for every table in the database that uses them. Running its suggestions strips 
AUTO_INCREMENT 
from all our fields. This of course breaks adding new rows. Interestingly, if 
you run it and then do 
sqldiff again, it still suggests these changes even though it has already made 
them.

Original issue reported on code.google.com by physicsn...@gmail.com on 7 Jul 2009 at 8:26