Fix for bug #928696 using binary protocol and failed server where subsequent requests never realized the server had recovered.

The Launchpad bug is incorrectly marked as fixed.  This appears to actually fix it.

Launchpad bug:  https://bugs.launchpad.net/libmemcached/+bug/928696
Proposed fix:  https://bugs.launchpad.net/libmemcached/+bug/928696/comments/9