- Make sure we log when an exception occurs in the squashing code

- Have queue file always try to return any remaining data in the buffer
- Remove the raise of the exception when we get an empty tar file

util/queuefile.py

@@ -20,7 +20,9 @@ class QueueFile(object):
 
   def read(self, size=8192):
     if self._closed or self._done:
-      return None
+      buf = self._buffer[0:size]
+      self._buffer = self._buffer[size:]
+      return buf
 
     while len(self._buffer) < size:
       result = self._queue.get(block=True)