[Cake] cake srchost/dsthost stopped working?

[Pete Heist]

It seems like Cake's srchost and dsthost keywords may have stopped
working some time between kernel 5.4 and 5.10.

When the bug occurs, there seems to not be fairness between hosts, but
rather fairness between flows. It reproduces on any 5.10 series kernel
I've tried, and does not reproduce on any 5.4 series or lower. Here's a
standalone script to reproduce it with netns, and some sample output:

https://www.heistp.net/downloads/cake-hostfair/

It creates competition from one IP to two IPs, and from two IPs to one
IP, using the src/dsthost keywords as appropriate. It also tests
fq_codel with a tc-flow filter, and cake *dual*-(src|dst)host, which
are both unaffected by this.

Any ideas?

Pete