Make repository URI creation work regardless of "repository" transaction order

Summary: Fixes T11276. This feels slightly iffy (we attachRepository() here, and also when applying the TYPE_REPOSITORY transaction) but simpler than trying to reorder things.

Test Plan: Created a repository URI with transactions in ["uri", "repository"] order.

Reviewers: chad, avivey

Reviewed By: avivey

Maniphest Tasks: T11276

Differential Revision: https://secure.phabricator.com/D16237