Committing file in .gitattributes but with no added keys commits plaintext

With version 0.5.0, I clone a repo with a `.gitattributes` file that matches a missing file. The repo has no added PGP keys. Even if I run `git-crypt init`, if I add the previous missing file and commit it, it's committed in plain text (which can be checked by cloning this local repo again somewhere else and running `git-crypt status -e` there).

I know that committing such file is pointless without added keys, but to avoid incidents, git-crypt could check before committing a supposedly encrypted file that it won't be encrypted, and produce an error.

Thank you!