Unsuccessfull deployment-scanner:add operation changes runtime state

Steps to reproduce:

1) Start standalone server
2) Issue:
/subsystem=deployment-scanner/scanner=testScanner:add(scan-interval=2000,path="/noexisiting")
where /noexisting is some incorrect path
3) Issue:
/subsystem=deployment-scanner/scanner=testScanner:add(scan-interval=2000,path="/tmp/test")
where /tmp/test is a valid path

I think that the expected result would be that the step 2 fails and it does not affect runtime nor configuration model.

The result of step 3 should be then a success however it is actually a failure:

08:45:25,421 ERROR [org.jboss.as.controller] (pool-3-thread-8) Operation ("add") failed - address: ([
("subsystem" => "deployment-scanner"),
("scanner" => "testScanner")
]): org.jboss.msc.service.DuplicateServiceException: Service jboss.server.deployment.scanner.testScanner.path is already registered
at org.jboss.msc.service.ServiceRegistrationImpl.setInstance(ServiceRegistrationImpl.java:154) [jboss-msc-1.0.1.GA.jar:1.0.1.GA]
at org.jboss.msc.service.ServiceControllerImpl.startInstallation(ServiceControllerImpl.java:226) [jboss-msc-1.0.1.GA.jar:1.0.1.GA]
at org.jboss.msc.service.ServiceContainerImpl.install(ServiceContainerImpl.java:560) [jboss-msc-1.0.1.GA.jar:1.0.1.GA]
at org.jboss.msc.service.ServiceTargetImpl.install(ServiceTargetImpl.java:201) [jboss-msc-1.0.1.GA.jar:1.0.1.GA]
at org.jboss.msc.service.ServiceControllerImpl$ChildServiceTarget.install(ServiceControllerImpl.java:2211) [jboss-msc-1.0.1.GA.jar:1.0.1.GA]