The way charm libraries generally function means that charm authors end up with local versions of third party libraries, which is by design. Some people have recently struggled with the contribution/feedback method and made changes to third-party library files *locally*, then had issues that the original library author has struggled to debug/replicate due to disceprancies. Charmcraft could help solve this by warning in the lint stage if a library has been changed from the original file that was downloaded as part of `charmcraft fetch-lib`.