The old pattern would match the following filenames:

• *Dockerfile
• *Dockerfile.*

This is because the pattern does not start with a slash indicating the beginning of the basename. Personally this led to a few false positives, like for example "siren-dockerfile.el" that sets up and configures dockerfile-mode in my Emacs configuration.

This change restricts the patterns to:

• Dockerfile
• Dockerfile.*
• *.dockerfile

I believe this is still wide enough to capture all common naming conventions for Dockerfiles.