Instead of assuming that a transaction will
correctly complete before it actually does we
should be smarter about this and inspect the
result to determine if it actually did and only
if it did should we set the committed flag.
Fixes issue 222

To ensure we reliably handle when a transaction fails
we should use the checked_commit() helper function instead
of the currently not fully exception handling kazoo
transaction commit function.
This should be addressed in the future with:
- python-zk/kazoo#224
- python-zk/kazoo#225
Those have not merged yet (or been released) so we need
to use a similar function in the meantime.
Change-Id: Icf83b7d4955c11227e733287170a7bd3ab372bd2

Project: openstack/taskflow  70d9199ea374b558a9918089de94af0b6c76811b
Use checked_commit() around consume() and abandon()
To ensure we reliably handle when a transaction fails
we should use the checked_commit() helper function instead
of the currently not fully exception handling kazoo
transaction commit function.
This should be addressed in the future with:
- python-zk/kazoo#224
- python-zk/kazoo#225
Those have not merged yet (or been released) so we need
to use a similar function in the meantime.
Change-Id: Icf83b7d4955c11227e733287170a7bd3ab372bd2