We added (and saved), then removed the cloudbees-deployer plugin from a build. Then, when we ran the job, it failed with this error:

Found mavenVersion 2.2.1 from file jar:file:/opt/maven/apache-maven-2.2.1/lib/maven-2.2.1-uber.jar!/META-INF/maven/org.apache.maven/maven-core/pom.properties
ERROR: Processing failed due to a bug in the code. Please report this to jenkins-users@googlegroups.com
java.lang.NullPointerException
at hudson.model.AbstractBuild$AbstractRunner.preBuild(AbstractBuild.java:667)
at hudson.maven.MavenModuleSetBuild$RunnerImpl.doRun(MavenModuleSetBuild.java:555)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:431)
at hudson.model.Run.run(Run.java:1362)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:432)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:145)

Looking at the config.xml for the job, I see this:

<publishers>
<null/>
</publishers>

It's not clear to me if this is a bug in the plugin or Jenkins itself.