We always copy paste the entire URL to the issue in the last line instead of just #123.

1. This makes it easy to open the issue when you're browsing the repo somewhere other than your issue tracker — I could just cmd-click on Fixes https://github.com/slashsBin/styleguide-git-commit-message/issues/1 in the terminal while reading the git log.
2. It allows you to migrate to a new issue tracker (such as github to gitlab) without any confusion.