Steps to reproduce:

1-In any page which has more than 50 revisions in its history, click on "Earliest" to display the oldest 50 revisions.

2-You will notice that the "rollback" link will appear beside the "undo" link for the top revision.

3-When clicking on the rollback link, rollback fails.

The rollback link should not appear.

For an example see the provided URL (history of en.WP sandbox).

Version: unspecified
Severity: enhancement
URL: http://en.wikipedia.org/w/index.php?title=Wikipedia:Sandbox&dir=prev&action=history