The Receiver._ensure_flush() method in ssync_receiver.py has
the following comment:
Sends a blank line sufficient to flush buffers.
This is to ensure Eventlet versions that don't support
eventlet.minimum_write_chunk_size will send any previous data
buffered.
If https://bitbucket.org/eventlet/eventlet/pull-request/37
ever gets released in an Eventlet version, we should make
this yield only for versions older than that.
The reference pull request was included with eventlet 0.14 [1] and
swift now requires >=0.16.1 so it is safe to remove _ensure_flush()
and save > 8k bytes per SSYNC response.
[1] 4bd654205a
Change-Id: I367e9a6e92b7ea75fe7e5795cded212657de57ed
191f2a00bd