more error handling in transfer: error on close

[dustin]

2010-05-19 09:38:40-0700 [Broker,2,192.168.10.25] Peer will receive following PB traceback:
2010-05-19 09:38:40-0700 [Broker,2,192.168.10.25] Unhandled Error
        Traceback (most recent call last):
          File "/usr/lib64/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-x86_64.egg/twisted/spread/banana.py", line 146, in gotItem
            self.callExpressionReceived(item)
          File "/usr/lib64/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-x86_64.egg/twisted/spread/banana.py", line 111, in callExpressionReceived
            self.expressionReceived(obj)
          File "/usr/lib64/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-x86_64.egg/twisted/spread/pb.py", line 514, in expressionReceived
            method(*sexp[1:])
          File "/usr/lib64/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-x86_64.egg/twisted/spread/pb.py", line 826, in proto_message
            self._recvMessage(self.localObjectForID, requestID, objectID, message, answerRequired, netArgs, netKw)
        --- <exception caught here> ---
          File "/usr/lib64/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-x86_64.egg/twisted/spread/pb.py", line 840, in _recvMessage
            netResult = object.remoteMessageReceived(self, message, netArgs, netKw)
          File "/usr/lib64/python2.5/site-packages/Twisted-8.2.0-py2.5-linux-x86_64.egg/twisted/spread/flavors.py", line 114, in remoteMessageReceived
            state = method(*args, **kw)
          File "/var/lib/buildbot/run/master/master/prefix/lib/buildbot-latest-py2.5.egg/buildbot/steps/transfer.py", line 50, in remote_close
            self.fp.close()
        exceptions.IOError: [Errno 122] Disk quota exceeded

[Dustin J. Mitchell]

Handle errors on master-side close in FileUpload?

A file isn't truly uploaded until the file on the master is closed, and thus flushed. Fixes #847

Changeset: 4f3314d44c6820643ebec61ae620e854a9ab7dec