Setting a nonempty contextPath turned up a couple problems in the test harness; goTo must be given a relative path.
https://ci.jenkins-ci.org/job/jenkins_main_trunk/2602/testReport/junit/hudson.model/JobTest/readPermission/
com.gargoylesoftware.htmlunit.FailingHttpStatusCodeException: 404 Not Found for http://localhost:47898/jenkins//j_acegi_security_check
	at com.gargoylesoftware.htmlunit.WebClient.throwFailingHttpStatusCodeExceptionIfNecessary(WebClient.java:549)
	at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:333)
	at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:357)
	at com.gargoylesoftware.htmlunit.html.HtmlForm.submit(HtmlForm.java:196)
	at org.jvnet.hudson.test.JenkinsRule$WebClient.login(JenkinsRule.java:1776)
	at org.jvnet.hudson.test.JenkinsRule$WebClient.login(JenkinsRule.java:1788)
	at hudson.model.JobTest.readPermission(JobTest.java:182)
Merge branch 'master' of github.com:jenkinsci/jenkins