Revert "fix broken retry logic for failed offset resets"
Revert "fix broken retry logic for failed offset resets"

This reverts commit 4cbe0a16407e2edcc7336e404c4f102269a9dd09.

Those changes resulted in KeyErrors because they perform a flush of
owned_partition_offsets when that is still needed by _handle_success()
later.  I'll try to commit an alternative fix for the problem.

benauthor/pykafka,yungchin/pykafka,appsoma/pykafka,wikimedia/operations-debs-python-pykafka,thedrow/samsa,aeroevan/pykafka,sontek/pykafka,sontek/pykafka,thedrow/samsa,benauthor/pykafka,sammerry/pykafka,aeroevan/pykafka,vortec/pykafka,jofusa/pykafka,appsoma/pykafka,yungchin/pykafka,wikimedia/operations-debs-python-pykafka,sammerry/pykafka,jofusa/pykafka,wikimedia/operations-debs-python-pykafka,vortec/pykafka,thedrow/samsa,benauthor/pykafka