python3.9 failing?

[Russell VT]

On Thu, Dec 23, 2021 at 12:52 AM Marco Atzeri <marco.atzeri@gmail.com>
wrote:

> On 23.12.2021 06:50, Russell VT wrote:
> > On Tue, Dec 21, 2021 at 6:34 AM Achim Gratz <Stromeko@nexgo.de> wrote:
> >
> >> Marco Atzeri writes:
> >>> Without Python 3.9  installed python3 should link by default to the
> >>> next in the line (likely 3.8)
> >>
> >> While python3 still defaults to python38 alternatives should probably
> >> prioritize 38 over 39?
> >
> >
> > That's how I "fixed" mercurial on my own installation, as it was
> > complaining about missing the "parsers" module, from inside the Python
> 3.9
> > libraries, IIRC.
>
> Thanks for the report.
> It is caused by:
>
> $ head /usr/bin/hg -n 20
> #!/usr/bin/python3
>                   ^^ default 3.9
> ....
>
> libdir = '../lib/python3.8/site-packages'
>                         ^^ but really need 3.8
>

Thanks... python3 defaults to whatever you have "alternatives" set to...
looks like python's libdir doesn't quite obey those alternatives, though?


> No surprise is not working.
>
> A simple workaround is:
>

Simpler (and more-complete) workaround is:

% /usr/sbin/alternatives.exe --set python3 /usr/bin/python3.8
% /usr/sbin/alternatives.exe --set python /usr/bin/python3.8
% /usr/sbin/alternatives.exe --display python3
python3 - status is manual.
 link currently points to /usr/bin/python3.8
/usr/bin/python3.8 - priority 38
/usr/bin/python3.6 - priority 36
/usr/bin/python3.7 - priority 37
/usr/bin/python3.9 - priority 39
Current `best' version is /usr/bin/python3.9.


Read: that way, when you can't figure out why the "next python upgrade"
isn't working, you only need to go to the very first stop you should be
looking (ie /etc/alternatives), and not some random link that may or may
not always be the first one in your path.

Cheers -
RVT

-- 
Russell M. Van Tassell <russellvt@gmail.com>