Fix next_uri
Summary: we were using the "path" as the next_uri and that drops some delicious get parameters
Test Plan: see T1140; basically re-ran the steps listed there and they passed!
Reviewers: epriestley, njhartwell
Reviewed By: epriestley
CC: aran, Koolvin
Maniphest Tasks: T1140, T1009
Differential Revision: https://secure.phabricator.com/D2299