Correctly handle case where no ssh keys are found

Summary: If no ssh keys are in phabricator, bin/ssh-auth errors with undefined `$lines`. This fixes that case and explicitly tells the user no rows were found.

Test Plan: Ran bin/ssh-auth before and after change with no ssh keys in the system. Error goes away after change.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: epriestley

CC: epriestley, aran, Korvin

Differential Revision: https://secure.phabricator.com/D7675

Author: Firehed

scripts/ssh/ssh-auth.php

@@ -15,6 +15,11 @@
   $user_dao->getTableName(),
   $ssh_dao->getTableName());
 
+if (!$rows) {
+  echo pht("No keys found.")."\n";
+  exit(1);
+}
+
 $bin = $root.'/bin/ssh-exec';
 foreach ($rows as $row) {
   $user = $row['userName'];