Fix a translation string

Summary: Fixes T7672. This had two %d conversions but only one parameter.

Test Plan: Adjusted limit to 0, viewed a merge, saw proper message.

Reviewers: chad, btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7672

Differential Revision: https://secure.phabricator.com/D12180