More specific idb failure logging
More specific idb failure logging

Summary: The "Conflict in temp dir" message was misleading when there were 0, rather than >1 file. This fixes that error message.

Reviewed By: passy

Differential Revision: D15716247

fbshipit-source-id: 572addf99f623cdcffd7602dd3935bb69a50d047

facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper,facebook/flipper