exception in phase 'conversion' if META-INF files contain comment headers

The following script makes Grovy 2.4.6 exit with the message "Caught: BUG! exception in phase 'conversion' in source unit /path-to-code/conversion.groovy' # Licensed to the Apache Software Foundation (ASF) under one or more":

@GrabResolver(name='jenkins', root='http://repo.jenkins-ci.org/releases')
@Grapes([
@Grab(group='com.google.inject', module='guice', version='4.0-beta'),
@Grab(group='org.springframework', module='spring-beans', version='3.0.5.RELEASE'),
@Grab(group='org.jenkins-ci.main', module='jenkins-core', version='2.1')
])

import java.lang.String

The stack trace prints when run with --debug is:

BUG! exception in phase 'conversion' in source unit '/path-to-code/conversion.groovy' # Licensed to the Apache Software Foundation (ASF) under one or more
at org.codehaus.groovy.control.CompilationUnit.applyToSourceUnits(CompilationUnit.java:935)
at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:593)
at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:569)
at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:546)
at groovy.lang.GroovyClassLoader.doParseClass(GroovyClassLoader.java:298)
at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:268)
at groovy.lang.GroovyShell.parseClass(GroovyShell.java:688)
at groovy.lang.GroovyShell.run(GroovyShell.java:517)
at groovy.lang.GroovyShell.run(GroovyShell.java:507)
at groovy.ui.GroovyMain.processOnce(GroovyMain.java:652)
at groovy.ui.GroovyMain.run(GroovyMain.java:384)
at groovy.ui.GroovyMain.process(GroovyMain.java:370)
at groovy.ui.GroovyMain.processArgs(GroovyMain.java:129)
at groovy.ui.GroovyMain.main(GroovyMain.java:109)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.codehaus.groovy.tools.GroovyStarter.rootLoader(GroovyStarter.java:109)
at org.codehaus.groovy.tools.GroovyStarter.main(GroovyStarter.java:131)
Caused by: java.lang.ClassNotFoundException: # Licensed to the Apache Software Foundation (ASF) under one or more
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:677)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:787)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:775)
at groovy.lang.GroovyClassLoader$loadClass$0.call(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
at groovy.grape.GrapeIvy$_processRunners_closure4.doCall(GrapeIvy.groovy:341)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:294)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1021)
at groovy.lang.Closure.call(Closure.java:426)
at groovy.lang.Closure.call(Closure.java:442)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2030)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2015)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2056)
at org.codehaus.groovy.runtime.dgm$162.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:274)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:56)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
at groovy.grape.GrapeIvy.processRunners(GrapeIvy.groovy:340)
at groovy.grape.GrapeIvy$processRunners$3.callCurrent(Unknown Source)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCallCurrent(CallSiteArray.java:52)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:154)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:182)
at groovy.grape.GrapeIvy.processOtherServices(GrapeIvy.groovy:325)
at groovy.grape.GrapeIvy$processOtherServices$2.callCurrent(Unknown Source)
at groovy.grape.GrapeIvy.grab(GrapeIvy.groovy:266)
at groovy.grape.Grape.grab(Grape.java:167)
at groovy.grape.GrabAnnotationTransformation.visit(GrabAnnotationTransformation.java:378)
at org.codehaus.groovy.transform.ASTTransformationVisitor$3.call(ASTTransformationVisitor.java:321)
at org.codehaus.groovy.control.CompilationUnit.applyToSourceUnits(CompilationUnit.java:931)
... 19 more