Augmenting a 'uses grouping' within a grouping fails

http://git.opendaylight.org/gerrit/2178

This is slightly contrived, because we augment an instance of a grouping to contain a the grouping itself. This fails with:

[ERROR] yang-to-sources: Unable to generate sources with org.opendaylight.yangtools.maven.sal.api.gen.plugin.CodeGeneratorImpl generator
java.lang.IllegalStateException: Grouping SchemaPath [path=[(urn:opendaylight:params:xml:ns:yang:rsvp?revision=2013-08-20)exclude-route-subobjects], absolute=true]is not resolved for Exrs
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.addImplementedInterfaceFromUses(BindingGeneratorImpl.java:2930)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.addDefaultInterfaceDefinition(BindingGeneratorImpl.java:2569)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.resolveContainerSchemaNode(BindingGeneratorImpl.java:2471)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.addSchemaNodeToBuilderAsMethod(BindingGeneratorImpl.java:1856)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.resolveDataSchemaNodesAugmented(BindingGeneratorImpl.java:1771)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.generateTypesFromAugmentedChoiceCases(BindingGeneratorImpl.java:2097)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.augmentationToGenTypes(BindingGeneratorImpl.java:1243)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.processUsesAugments(BindingGeneratorImpl.java:369)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.allGroupingsToGenTypes(BindingGeneratorImpl.java:1008)
at org.opendaylight.yangtools.sal.binding.generator.impl.BindingGeneratorImpl.generateTypes(BindingGeneratorImpl.java:220)
at org.opendaylight.yangtools.maven.sal.api.gen.plugin.CodeGeneratorImpl.generateSources(CodeGeneratorImpl.java:42)
at org.opendaylight.yangtools.yang2sources.plugin.YangToSourcesProcessor.generateSourcesWithOneGenerator(YangToSourcesProcessor.java:222)
at org.opendaylight.yangtools.yang2sources.plugin.YangToSourcesProcessor.generateSources(YangToSourcesProcessor.java:171)
at org.opendaylight.yangtools.yang2sources.plugin.YangToSourcesProcessor.execute(YangToSourcesProcessor.java:75)
at org.opendaylight.yangtools.yang2sources.plugin.YangToSourcesMojo.execute(YangToSourcesMojo.java:102)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
[ERROR] yang-to-sources: One or more code generators failed, including failed list(generatorClass=exception)

{org.opendaylight.yangtools.maven.sal.api.gen.plugin.CodeGeneratorImpl=java.lang.IllegalStateException}