Am I the only one who think this is a stupid UI decision by Atlassian?
When you paste a GitHub URL into a Jira issue, Jira is parsing the link and insist you connect your GitHub account to preview the link.
In earlier versions you could simply have the URL like this
https://github.com/szimek/signature_pad
Not everybody on our team have a GutHub account, and neither should one be needed just because we reference to a 3rd party library.