(stable) Fix a couple more "URI->alter()" callsites in paging code

Summary: grep had a hard time finding these.

Test Plan: Will just hotfix this since I'm still reasonably in the deploy window, this currently fatals: https://secure.phabricator.com/search/query/_dgatshiRBSy/#R

Reviewers: amckinley

Differential Revision: https://secure.phabricator.com/D20186