Latest STABLE locks up on boot for me

[Pete French]

I just upgraded to STABLE, having been running r338093 since the end of August,
and was su[psised when it locked up on boot for me. By which I mean the keyboard
is unresponsible and the SATA drive access LED is on permamently.

I have a small encryopted partition, and the boot gets as far as asking for
the password for that, but afterwards it then freezes with the last thing I
see being the line about unblocking the random device.  It does this
even if I boot in safe mode.

The machine is booting ZFS (unencrypted) and is a Ryzen CPU. I will
start trying to work out where the offending commit is, but if anyone
has an insight which might help shortcut the process then please let me know.

cheers,m

-pete.