Question about `checkHost`

[Ben Alkov]

Hi, I have a question about `checkHost`...
 
AFAIU:
 
- kojid's `main` continually loops over daemon.py::TaskManager::getNextTask()
- getNextTask() calls daemon.py::TaskManager::takeTask() (when appropriate)
- and takeTask() calls back into kojid's build-task-class-specific (i.e. some children
of BaseBuildTask) `checkHost()`
 
The question: Is it the case that a failed `checkHost()` call will simply cause a builder
to
skip that task and go on to the next, *eventually coming back to check that task
again*?
 
Some context:
 
OSBS is being redesigned (reimplemented as well, at this point), and the feature
that we had in the old OSBS which would "pipeline" multiple tasks created from
the exact same repo/branch will no longer work[1].
 
We're looking at "abusing" `checkHost` by defining an override in OSBS'
koji-containerbuild[2] builder to check existing 'OPEN' tasks before taking up a
new one.
 
Our primary concern is making sure that a task which is being skipped by
the builders (because it failed the `checkHost` check) will still be picked up
once `checkHost` clears.
 
[1] Primarily to avoid the situation where build 1 starts, then build 2, both
from exactly the same repo/branch, but for reasons build *2* finishes first
(happens all the time...), and build *1* gets tagged ':latest' in the registry -
this is surprising to end-users who expect the last *requested* build to get the
':latest' tag
[2] https://github.com/containerbuildsystem/koji-containerbuild