make "browse in diffusion" action work for commits in branches other than master

Summary: we do this by passing the "seenOnBranches" commit data detail through the stack

Test Plan: browse in diffusion link worked for non-master checkins under git

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1949

Differential Revision: https://secure.phabricator.com/D3853

src/applications/diffusion/controller/DiffusionCommitController.php

@@ -269,6 +269,10 @@ final class DiffusionCommitController extends DiffusionController {
       $change_list->setRenderURI('/diffusion/'.$callsign.'/diff/');
       $change_list->setRepository($repository);
       $change_list->setUser($user);
+      // pick the first branch for "Browse in Diffusion" View Option
+      $branches     = $commit_data->getCommitDetail('seenOnBranches');
+      $first_branch = reset($branches);
+      $change_list->setBranch($first_branch);
 
       $change_list->setStandaloneURI(
         '/diffusion/'.$callsign.'/diff/');