Update to 7.x-2.11 leaves site with "Security update required" warning

Updating to 7.x-2.11 leaves the site with a "Security update required!" warning, and an older recommended version of 7.x-2.10.

This is presumably because 2.11 has been pulled because of this issue, so it will presumably be fixed when 2.12 comes out. Just filing the issue with the symptoms in the title to make it easier for people who experience this to find it.