Pass correct number of parameters to pht() when closing a branch in Mercurial

Summary: Ref T5050. This fixes the immediate error (bad pht()) but doesn't fix the other error (can't `--close-branch`) yet.

Test Plan: Pushed a `--close-branch` commit, got a first-level error instead of an error about an error.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T5050

Differential Revision: https://secure.phabricator.com/D9119