Squashed commits:
[73308b5] [FIXED JENKINS-27549] job loading can be broken by a NPE in a build trigger

Simple `<l:task post="true" href="someurl"/>` triggers post request as expected
but then proceeds to href as normal link to. If the URL accepts GET then request
is sent twice it if does not after POSTing on background user get
'POST is required' error.

- Typo
- Print error combined
- Set result only when phase like in other code parts.
- Test for expected error message in log

- Print publisher display name instead of class, so user can understand what publisher in UI was used and failed.
- Setter for artifact archiver shows how it handle status
- Minor typos
- Added test for stacktraces in build log

Starting in 4f24a027 (1.587-SNAPSHOT, before #1443 or stapler #39), nestedDescribableOverridingId passes.
nestedDescribableSharingClass fails given {stapler-class: D3, kind: d3a}.
(Stapler has no way of interpreting kind since it knows nothing of Descriptor, only implementation class names.)
In master (3080573a), both fail in the way reported (only kind is passed in).
After adding stapler-class back, nestedDescribableOverridingId passes again.

Besides failing in master, it also fails in 4e0af431 (merge of #1443), but passes in the 1.598-SNAPSHOT parent 239caf89.