[PATCH 4 of 4] revert: add a `drop` action

[Durham Goode]

On 9/10/14, 12:29 PM, Pierre-Yves David wrote:
> # HG changeset patch
> # User Pierre-Yves David <pierre-yves.david at fb.com>
> # Date 1409358323 -7200
> #      Sat Aug 30 02:25:23 2014 +0200
> # Node ID 2eeb360edc896fc011c062fba486c8abc3794557
> # Parent  84ecfe0c320d1ee0eff3d98074b57b3d168ff9e7
> revert: add a `drop` action
>
> This prevent the needs of a try except in the `_performrevert` code.
>
Queued this series to the clowncopter repo.