[tex-live] tlmgr returns 0 even on failure

[Dr. Clea F. Rees]

tlmgr update --all
...

Exits with 0 even though parts of the update process failed. In
particular, not all formats were successfully regenerated. (I think
this is because it is pulling in stuff from my person tex tree which is
messing things up.)

I think it should return a non-zero exit status in this case. I also
think the error messages regarding the specific failures and relevant
log location should be repeated at the end, if possible (but maybe it
isn't).

Question: how do I generate the missing formats by hand? I've never had
to do this before. I see tlmgr triggers
fmtutil-sys --missing
Is this enough? Or is a further step needed?

Thanks,
cfr