Summary: Ref T603. We might need a fine-grained CLI tool later on, but here's a bat we can bludgeon things with.
Test Plan:
- Ran `bin/policy unlock D12` (adjusted policies).
- Ran `bin/policy unlock rPca85c457ebcb` (got "not mutable" stuff).
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T603
Differential Revision: https://secure.phabricator.com/D7189