NumberFormatException in UndertowDeploymentInfoService when war is deployed

I compiled WildFly on a Windows box (Win7, x64, JDK 1.7.0_21 32bit). Starting the WildFly appserver without any app works fine.

Next I tried to deploy a war. However, I get the stacktrace below caused by a NumberFormatException.

14:59:29,806 ERROR [org.jboss.msc.service.fail] MSC000001: Failed to start service jboss.undertow.deployment.default-host./shop2.UndertowDeploymentInfoService: org.jboss.msc.service.StartException in service jboss.undertow.deployment.default-host./shop2.UndertowDeploymentInfoService: Failed to start service
at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1930) [jboss-msc-1.1.2.Final.jar:1.1.2.Final]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_21]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_21]
at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_21]
Caused by: java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:454) [rt.jar:1.7.0_21]
at java.lang.Integer.parseInt(Integer.java:527) [rt.jar:1.7.0_21]
at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService.createServletConfig(UndertowDeploymentInfoService.java:513)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService.start(UndertowDeploymentInfoService.java:200)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1974) [jboss-msc-1.1.2.Final.jar:1.1.2.Final]
at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1907) [jboss-msc-1.1.2.Final.jar:1.1.2.Final]
... 3 more