[Backport to 7.9] Occasional ComponentNotFoundException (renaming image)

When working in the CMS occasionally an error is thrown, in this case renaming an image. Same error shows in regression test runs.

Steps that resulted in this error
1) Login the CMS
2) Go to images, select image, Document/Rename
3) Type a new name and click OK, image is renamed, but a stacktrace is shown:

[INFO] [talledLocalContainer] 29.04.2015 11:27:52 ERROR http-nio-8080-exec-4 [DefaultExceptionMapper.mapUnexpectedExceptions:170] Unexpected error occurred
[INFO] [talledLocalContainer] org.apache.wicket.core.request.handler.ComponentNotFoundException: Component 'dialog:content:form:name-url:name' has been removed from page.
[INFO] [talledLocalContainer] at org.apache.wicket.core.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:178)
[INFO] [talledLocalContainer] at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:890)
[INFO] [talledLocalContainer] at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
[INFO] [talledLocalContainer] at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:261)