Code review comment for lp:~michihenning/persistent-cache-cpp/fix-copyright-xenial

We could do that, but we'd get many hundreds of errors in the log.

I have this on my todo list anyway. It affects this project, thumbnailer, unity-api, and unity-scopes-api, so it needs doing. All these projects have disabled the test the same way as here, so I'm a bit reluctant to make a change only here, seeing that it's a temporary work-around for the failure anyway.

Note that we won't accidentally release with missing copyright headers because that is tested separately by the build machinery.

I added a unit test for this originally mainly so we wouldn't only find out on Jenkins or in a silo when there was a problem with a copyright header.