local pod repository for testing

Is there a way to use `new_pod_repository` with a locally modified version of a pod, similar to how `local_repository` works? I tried using a relative file in the url field, and I then the podspec file could not be found. I provided a value for podspec_url, but it expects a label, so I had to copy the podspec into the repo. I saw some code related to url being a file, but maybe I'm not using it as intended. For now, I am pushing changes to a fork and bumping the version for each change.