[tlu] TLU critical update still faliing

[Richard Koch]

Folks,

I got exactly the same error message on a 2016 Intel Mac running Mojave.
This is the machine on which I've built Intel TL binaries for several years now.
So nothing has changed at this end either. 

Note that tlmgr itself works fine, including updating itself, on all of these
machines. What fails on all of them is the script update-tlmgr-latest.sh,
and nobody would have known this except that Adam calls it rather
than tlmgr update --self in TeX Live Utility. (I didn't know that, but
luckily Herbert Schulz knew it.)

Dick