A queued deployment whose commit no longer validates (for example one
queued before an upgrade) made the job dispatch throw. The row stayed
in_progress, blocked every later deployment of the application, and
stopped the queue loop. Such a row is now marked failed with a log
entry and a failure notification, and the next queued deployment
starts.
An exception after the new container passed its health check (for
example in additional destinations, the next-deployment loop, or
notifications) made failed() remove the new container, which could be
the only one running. failed() now keeps a healthy new container, and
errors in the steps after a status change are logged without flipping
a finished deployment to failed.
