Recreation

Have 2 jobs:
Job 1 triggers Job 2 using the "Trigger/call builds on other projects"
Uses "Predefined parameter": test_loop=${test_loop}

Job 2 uses "Create a formatted version number" where:
"Environment Variable Name": test_loop
"Version Number Format String": ${test_loop}

Outcome

This causes the Job 2 to be stuck in an endless loop as test_loop keeps getting translated into ${test_loop} and tries to be translated again and again...

threadDump looks as follows:

 Executor #0 for master : executing test_endless_loop #5
"Executor #0 for master : executing test_endless_loop #5" Id=116 Group=main RUNNABLE
	at org.jvnet.hudson.tools.versionnumber.VersionNumberBuilder.formatVersionNumber(VersionNumberBuilder.java:341)
	at org.jvnet.hudson.tools.versionnumber.VersionNumberBuilder.setUp(VersionNumberBuilder.java:364)
...

I stumbled on this by accident and this configuration should be avoided, but still it causes a job to be stuck in an endless loop which could not be stopped.
Stopping it was only by restarting the server.