invoker unit tests fail

I get the following failure on my Mac:

testBuildShouldSucceed(org.apache.maven.shared.invoker.DefaultInvokerTest) Time elapsed: 1.058 sec <<< FAILURE!
junit.framework.AssertionFailedError: expected:<0> but was:<1>
at junit.framework.Assert.fail(Assert.java:47)
at junit.framework.Assert.failNotEquals(Assert.java:282)
at junit.framework.Assert.assertEquals(Assert.java:64)
at junit.framework.Assert.assertEquals(Assert.java:201)
at junit.framework.Assert.assertEquals(Assert.java:207)
at org.apache.maven.shared.invoker.DefaultInvokerTest.testBuildShouldSucceed(DefaultInvokerTest.java:44)
at org.apache.maven.shared.invoker.DefaultInvokerTest.testBuildShouldSucceed(DefaultInvokerTest.java:44)

The same issue is being seen in CI:
http://maven.zones.apache.org/continuum/surefireReport.action?buildId=13387&projectId=57#org.apache.maven.shared.invoker.DefaultInvokerTest

this is building the shared component.