Enforced dependencies errors updating to recent versions of Drupal 7

Problem/Motivation

While updating a Drupal 7.13 installation to Drupal 7.18, I ran across a couple of errors. The errors occurred when using Microsoft SQL, but not when using MySQL.

The upgrade error messages are:

system module
 
Update #7073
 •Failed: PDOException: SQLSTATE[42000]: [Microsoft][SQL Server Native Client 11.0][SQL Server]Object 'file_managed.uri' cannot be renamed because the object participates in enforced dependencies.: EXEC sp_rename :old, :new, :type; Array ( [:old] => file_managed.uri [:new] => uri_old [:type] => COLUMN ) in db_change_field() (line 2988 of C:\inetpub\wwwroot\DrupalKickstart\includes\database\database.inc).

and

node module
 
Update #7013
 •Failed: PDOException: SQLSTATE[42000]: [Microsoft][SQL Server Native Client 11.0][SQL Server]Object 'node.vid' cannot be renamed because the object participates in enforced dependencies.: EXEC sp_rename :old, :new, :type; Array ( [:old] => node.vid [:new] => vid_old [:type] => COLUMN ) in db_change_field() (line 2988 of C:\inetpub\wwwroot\DrupalKickstart\includes\database\database.inc).

Proposed resolution

Referencing the db_change_field() comments, "To maintain database portability, you have to explicitly recreate all indices and primary keys that are using the changed field". The comments go on to say that ALL affected keys (unique keys, in this instance) have to be dropped. I created a patch that drops the unique key and re-adds it after db_change_field() has run for both the system and node updates mentioned in the error.