Migration 002 sets the password created_at column to a TIMESTAMP type
with a server_default=sql.func.now(). There are a couple problems
that have been uncovered with this change:
* We cannot guarantee that func.now() will generate a UTC timestamp.
* For some older versions of MySQL, the default TIMESTAMP column will
automatically be updated when other columns are updated:
https://dev.mysql.com/doc/refman/5.5/en/timestamp-initialization.html
This patch fixes the problem by recreating the password created_at
column back to a DateTime type without a server_default:
1) Drop and recreate the created_at column
2) Update the created_at value
3) Set the created_at column as not nullable
Closes-Bug: #1621200
Change-Id: Id5c607a777afb6565d66a336028eba796e3846b2
(cherry picked from commit 32328de6e3)
b3fae7724d