Improve debugging information on ID uniqueness failure in isolated connection

test

Summary: @jungejason reported seeing test failures here. I can't reproduce them
and my read of the code doesn't suggest why they might be happening, but add a
little more debug info in hopes of chasing this down.

Test Plan:
  - Ran test in a loop for a long time, couldn't get it to fail.
  - Changed assertEquals() condition to force test to fail, verified output
message was informative.

Reviewers: jungejason, btrahan

Reviewed By: jungejason

CC: aran, epriestley, jungejason

Differential Revision: 1212

src/storage/connection/isolated/__tests__/AphrontIsolatedDatabaseConnectionTestCase.php

@@ -64,7 +64,10 @@ class AphrontIsolatedDatabaseConnectionTestCase
 
     $this->assertEqual(true, (bool)$id1, 'ID1 exists.');
     $this->assertEqual(true, (bool)$id2, 'ID2 exists.');
-    $this->assertEqual(true, $id1 != $id2, 'IDs are distinct.');
+    $this->assertEqual(
+      true,
+      $id1 != $id2,
+      "IDs '{$id1}' and '{$id2}' are distinct.");
   }
 
   private function newIsolatedConnection() {