IV Undefined Error for Some Builds

I have a GitHub repo, waffle_gcs, that requires Google Cloud credentials to perform certain integration tests. I have encrypted the file using the official documentation for doing so. Any branch that belongs to the repo directly, such as master, seems to build without a problem. When someone forks my project and submits a pull request, they get an “iv undefined” error during decryption.

It seems like this might be a problem with how Travis sets environment variables for forks of a project? I’m just guessing at this point, but because it consistently works with the master branch, and other branches that belong to the primary waffle_gcs repo, I would guess that the fact this is coming from a fork is the source of the problem. Is there any way to solve this?