Startup fails on WebLogic 10.3 with error "..InfrastructureException: Error occurred while starting Plugin Manager..."

Startup of JIRA 4.0 fails on WebLogic 10.3 with the following exception:

FATAL [atlassian.jira.upgrade.ConsistencyLauncher] A fatal error occured during initialisation. JIRA has been locked.
com.atlassian.jira.InfrastructureException: Error occurred while starting Plugin Manager. Unable to find required packages via classloader or servlet context scanning, most likely due to an application server bug.
at com.atlassian.jira.ComponentManager$PluginSystem.start(ComponentManager.java:1281)
at com.atlassian.jira.ComponentManager.quickStart(ComponentManager.java:224)
at com.atlassian.jira.ComponentManager.start(ComponentManager.java:210)
at com.atlassian.jira.upgrade.ConsistencyLauncher.launchConsistencyChecker(ConsistencyLauncher.java:63)
at com.atlassian.jira.upgrade.ConsistencyLauncher.contextInitialized(ConsistencyLauncher.java:42)
at weblogic.servlet.internal.EventsManager$FireContextListenerAction.run(EventsManager.java:465)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
...
Caused by: java.lang.IllegalStateException: Unable to find required packages via classloader or servlet context scanning, most likely due to an application server bug.
at com.atlassian.plugin.osgi.container.felix.ExportsBuilder.generateExports(ExportsBuilder.java:152)
at com.atlassian.plugin.osgi.container.felix.ExportsBuilder.determineExports(ExportsBuilder.java:70)
at com.atlassian.plugin.osgi.container.felix.FelixOsgiContainerManager.start(FelixOsgiContainerManager.java:218)
at com.atlassian.plugin.osgi.container.felix.FelixOsgiContainerManager.onStart(FelixOsgiContainerManager.java:183)
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 com.atlassian.plugin.event.impl.DefaultPluginEventManager$Listener.notify(DefaultPluginEventManager.java:196)
at com.atlassian.plugin.event.impl.DefaultPluginEventManager.broadcast(DefaultPluginEventManager.java:70)
at com.atlassian.plugin.manager.DefaultPluginManager.init(DefaultPluginManager.java:127)
at com.atlassian.jira.plugin.JiraPluginManager.start(JiraPluginManager.java:49)
at com.atlassian.jira.ComponentManager$PluginSystem.start(ComponentManager.java:1275)
... 40 more>

Deploying as an exploded WAR does not help.

However, a change to the class org.twdata.pkgscanner.InternalScanner according to the attached patch did the trick, but only for exploded WARs.