Cannot use stubbed methods in cleanup method if the test succeeds

Issue description

I'm trying to use a stubbed method in a cleanup method. This works if an assertion failed in the test, but not if the test succeeds.

How to reproduce

class UseStubInCleanupSpec extends Specification {

    def mock = Mock(java.util.function.Function)

    def setup() {
        mock.apply("a") >> { "b" }
    }

    def cleanup() {
        assert mock.apply("a") == "b"
    }

    def "run a successful test"() {
        expect:
        true
    }

    def "run a failing test"() {
        expect:
        false
    }

}

Java/JDK

1.8

Groovy version

2.3.10:indy

Operating System

Mac

IDE

IntelliJ

Gradle/Grails

compile 'org.spockframework:spock 1.0-groovy-2.3'

Start with the supplied UseStubInCleanupSpec reproducer and run both the successful and failing test methods on the stated Spock, Groovy, and JDK versions. Compare cleanup behavior in each case and trace the mock lifecycle; done means the stubbed method works during cleanup after a successful test without regressing the failing-test case.