build failure mainline

[Tom Tromey]

>>>>> "Andreas" == Andreas Tobler <toa@pop.agri.ch> writes:

Andreas> It was building 24hours ago. I'll look into it this
Andreas> evening. If anyone else has discovered it ....

I haven't seen it, but I haven't done a clean rebuild since a couple
days ago.  Could you file a PR for this and then send the number to
Mark as release-critical?  Please CC me on the email to Mark.

Tom