An update to a newer core version of Jenkins (1.480), because of the new Build Flow plugin, leads to an abort of the test suite.
ExternalResourceJenkinsTest.testCanEnableDisableOnNode() and testCantEnableDisableOnBuild() do have issues at:
HtmlPage page = web.getPage
There seems to be a problem with parsing the site, which leads to errors and aborts of the tests. These aborts seem to create so much garbage that further test can't be executed due to the lack of PermGen space. The quick fix is to comment out these 2 tests and do them manually.

I don't really know where the problem is, but I think there are 3 possibilites:
1. The plugin creates some invalid JavaScript that the Html-Parser can't handle. (I think that it's unlikely)
2. Jenkins does the invalid JavaScript.
3. The parser is broken.

To reproduce just change the parent version (Jenkins version) in the pom file to 1.480 and run mvn test.