I created a gist to store some casual changes to files. The gist is now at revision 14, and cannot save new changes.
The AJAX call shows an aborted message after trying to post to https://gist.github.com/AstDerek/<gist-id>
And a redirection to https://collector.githubapp.com/gist/page_view?dimensions[page]=https%3A%2F%2Fgist.github.com%2FAstDerek%2F<gist-id>&dimensions[title]=Gists&dimensions[referrer]=&dimensions[user_agent]=<browser-details>&dimensions[screen_resolution]=<res>&dimensions[pixel_ratio]=1&dimensions[browser_resolution]=<res>&dimensions[timestamp]=<ts>&&dimensions[actor_id]=<id>&dimensions[actor_login]=AstDerek&dimensions[actor_hash]=<some-hash>
It seems there is no limit on editions.
For example, one of my gists has 73 revisions.