I've decided to orphan fakeroot. I haven't used it for a long time, it's FTBFS with the latest glibc in rawhide and fixing the build issue only obscures the missing interception for new glibc interfaces.
I'm not sure how responsive upstream will be to the issue as they're the Debian maintainer. They've been slow to respond to my previous bug reports in the past.
Regards, Dominik