Confirmed break happens between 1.340 and 1.341

what's the use case for a job triggering itself? wouldn't this result in infinite builds, unless a build fails?

since parameterized-trigger 2.3 with hudson 1.341+ it uses the DependencyGraph feature from Hudson core to declare the dependencies.. this class specifically rejects self-dependencies. (DependencyGraph.java line 178)
maybe you can explain your usage, as I currently don't see why we'd change this.

Code changed in hudson
User: : mindless
Path:
trunk/hudson/main/core/src/main/java/hudson/model/DependencyGraph.java
http://jenkins-ci.org/commit/31935
Log:
[FIXED JENKINS-5981] allow plugins to add self-referencing project dependencies

still curious why you'd want to do that, but I didn't find any problems when I removed the DependencyGraph condition rejecting self-reference.. so made the change.
note this is a change in Hudson core, so you don't need a parameterized-trigger upgrade, just get Hudson 1.363 or higher when it comes out.

Yes, the infinite build thing is exactly what I want

We have a project with randomised tests that takes a seed, every time we restart it after a success it picks a different seed and does different tests.