Seems to have caused spurious timeout errors.
https://jenkins.ci.cloudbees.com/job/core/job/jenkins_main_trunk/1748/testReport/junit/hudson.scheduler/CronTabEventualityTest/testFirstSundayOfMonthWillBeEventuallyTriggeredWithinOneMonthAndOneWeek_0_/
java.lang.Exception: test timed out after 1000 milliseconds
	at java.io.UnixFileSystem.getBooleanAttributes0(Native Method)
	at java.io.UnixFileSystem.getBooleanAttributes(UnixFileSystem.java:242)
	at java.io.File.exists(File.java:772)
	at sun.misc.URLClassPath$FileLoader.getResource(URLClassPath.java:1072)
	at sun.misc.URLClassPath.getResource(URLClassPath.java:199)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:358)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	at hudson.scheduler.CronTab.set(CronTab.java:87)
	at hudson.scheduler.CronTab.<init>(CronTab.java:83)
	at hudson.scheduler.CronTab.<init>(CronTab.java:66)
	at hudson.scheduler.CronTabEventualityTest.checkEventuality(CronTabEventualityTest.java:113)
	at hudson.scheduler.CronTabEventualityTest.testFirstSundayOfMonthWillBeEventuallyTriggeredWithinOneMonthAndOneWeek(CronTabEventualityTest.java:109)