MyPluginProjectSpec.apply-does-not-throw-exceptions always fails under Windows presumably due to open file handle

[reinholdfuereder]

MyPluginProjectSpec:

class MyPluginProjectSpec extends PluginProjectSpec {

Test failure:

: Unable to delete file D:\workspaces\testautomation\buildsystem\gradle\...\plugins\...\build\test\MyPluginProjectSpec\apply-does-not-throw-exceptions_1\userHome\native\19\windows-i386\native-platform.dll
    at org.apache.tools.ant.taskdefs.Delete.handle(Delete.java:719)
    at org.apache.tools.ant.taskdefs.Delete.removeDir(Delete.java:768)
    at org.apache.tools.ant.taskdefs.Delete.removeDir(Delete.java:764)
    at org.apache.tools.ant.taskdefs.Delete.removeDir(Delete.java:764)
    at org.apache.tools.ant.taskdefs.Delete.removeDir(Delete.java:764)
    at org.apache.tools.ant.taskdefs.Delete.removeDir(Delete.java:764)
    at org.apache.tools.ant.taskdefs.Delete.execute(Delete.java:586)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:292)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at groovy.util.AntBuilder.performTask(AntBuilder.java:319)
    at groovy.util.AntBuilder.nodeCompleted(AntBuilder.java:264)
    at groovy.util.BuilderSupport.doInvokeMethod(BuilderSupport.java:147)
    at groovy.util.AntBuilder.doInvokeMethod(AntBuilder.java:203)
    at groovy.util.BuilderSupport.invokeMethod(BuilderSupport.java:64)
    at nebula.test.ProjectSpec.cleanup(ProjectSpec.groovy:37)

My current workaround is to override a method of PluginProjectSpec in MyPluginProjectSpec:

import org.apache.tools.ant.taskdefs.condition.Os

...

    boolean deleteProjectDir() {
        return !Os.isFamily(Os.FAMILY_WINDOWS)
    }

But now it is not delete for each test case, and I would hope a fix (or workaround?) in PluginProjectSpec is better (and helps in general).