Fix repository URI generation for SVN commit identifiers represented with integer types

Summary:
Ref T13588. See PHI2198. Some pathways represent SVN commit identifiers (which are numeric) with integers; these raise an exception in `phutil_nonempty_string()`, which is strict.

(Ideally, commit identifiers wouldn't have mixed types, but that's a dramatically less practical change.)

Test Plan: Will deploy.

Maniphest Tasks: T13588

Differential Revision: https://secure.phabricator.com/D21852

Author: epriestley

src/applications/repository/storage/PhabricatorRepository.php

@@ -752,7 +752,7 @@ public function generateURI(array $params) {
     }
 
     $raw_commit = $commit;
-    if (phutil_nonempty_string($commit)) {
+    if (phutil_nonempty_scalar($commit)) {
       $commit = str_replace('$', '$$', $commit);
       $commit = ';'.phutil_escape_uri($commit);
     }