NPE if "sonar.gallio.coverage.tool" is set to "none"

Caused by: java.lang.NullPointerException
        at org.sonar.dotnet.tools.gallio.GallioCommandBuilder.generateGallioArguments(GallioCommandBuilder.java:276)
        at org.sonar.dotnet.tools.gallio.GallioCommandBuilder.toCommand(GallioCommandBuilder.java:216)
        at org.sonar.dotnet.tools.gallio.GallioRunner.execute(GallioRunner.java:92)
        at org.sonar.plugins.csharp.gallio.GallioSensor.executeRunner(GallioSensor.java:194)
        at org.sonar.plugins.csharp.gallio.GallioSensor.analyse(GallioSensor.java:162)
        at org.sonar.batch.phases.SensorsExecutor.execute(SensorsExecutor.java:64)
        at org.sonar.batch.phases.Phases.execute(Phases.java:93)
        at org.sonar.batch.bootstrap.ProjectModule.doStart(ProjectModule.java:127)
        at org.sonar.batch.bootstrap.Module.start(Module.java:83)
        at org.sonar.batch.bootstrap.BatchModule.analyze(BatchModule.java:116)
        at org.sonar.batch.bootstrap.BatchModule.analyze(BatchModule.java:111)
        at org.sonar.batch.bootstrap.BatchModule.doStart(BatchModule.java:106)
        at org.sonar.batch.bootstrap.Module.start(Module.java:83)
        at org.sonar.batch.bootstrap.BootstrapModule.doStart(BootstrapModule.java:121)
        at org.sonar.batch.bootstrap.Module.start(Module.java:83)
        at org.sonar.batch.Batch.execute(Batch.java:104)
        at org.sonar.runner.internal.batch.Launcher.executeBatch(Launcher.java:69)
        at org.sonar.runner.internal.batch.Launcher.execute(Launcher.java:61)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.sonar.runner.Runner.delegateExecution(Runner.java:285)
        ... 3 more