Steps to repro:

1) Install https://wiki.jenkins-ci.org/display/JENKINS/Exclusive+Execution+Plugin
2) Create a multi-configuration project
3) Configure the project from step 2, in the "Configuration Matrix section" click "Add axis".
4) Choose "Slaves".
5) At this point you might be bitten by https://issues.jenkins-ci.org/browse/JENKINS-9689 - see comments for the workaround
6) Choose at least 2 build servers (ie. master and slave).
7) Build the project from step 2.

The project is dispatched to both the master and slave build servers, but neither ever complete.

Slave's console output says:
09:47:13 [ExclusiveBuildWrapper] Executing on slavePC1
09:47:13 [ExclusiveBuildWrapper] Putting Jenkins in shutdown mode...

Master's console output says:
09:47:13 [ExclusiveBuildWrapper] Executing on master
09:47:13 [ExclusiveBuildWrapper] Putting Jenkins in shutdown mode...

The system never exits from this state.