If we send the terminator on an error, it looks like we have actually
completed the upload, when that was not actually the case, we have
failed, and ideally we want glance to notice and mark the snapshot as
failed.
This partly reverts the following commit:
e039b036b5e9dbaff8b37f7ab22c209b71bdc182
It is not a full revert of the above commit, and some of the refactoring
and error handling changes are still useful.
Closes-Bug: #1398826
Change-Id: Ib608a32556135a5b7e666d02c4ee77722ea6e07c
979d1116fe