Gradle: set variable in taskGraph.whenReady

My build script has this code:

def includePatchFrom = "WTF?!"

task patchWebXml(type: Exec) {
    executable "perl"
    args "scripts/patch.pl", includePatchFrom
}

gradle.taskGraph.whenReady { taskGraph ->
    if (taskGraph.hasTask(webtestWar)) {
        includePatchFrom = "resources/webtest"
    }
    else {
        includePatchFrom = "resources/production"
    }
}

      

        
        
        
      

    

If I understand correctly http://www.gradle.org/docs/current/userguide/tutorial_using_tasks.html , I have to set this variable includePatchFrom

in the closure whenReady

, but it just keeps its initial value:

...
:patchWebXml
...
Starting process 'command 'perl''. Working directory: /Users/robert/ Command: perl scripts/patch.pl WTF?!
Successfully started process 'command 'perl''
Cannot read WTF?!: No such file or directory at scripts/patch.pl line 43, <$F> line 14.
:patchWebXml FAILED

      

        
        
        
      

    

In the println outputs, I can tell I am includePathFrom

getting the correct value. It looks like the exec task has already used the old value includePatchFrom

and is not affected when the close completes whenReady

.

What am I missing here and how can I use a different patch file depending on whether it is a production or test build?