[PATCH v2] tag: Automatically limit to messages whose tags will actually change.

[David Bremner]

On Wed,  9 Nov 2011 08:44:35 -0500, Austin Clements <amdragon at MIT.EDU> wrote:
> This optimizes the user's tagging query to exclude messages that won't
> be affected by the tagging operation, saving computation and IO for
> redundant tagging operations.

Pushed, 

d