Bug#1101992: esys-particle: misbuilds when built with Python 3.13 only

[Graham Inggs]

Source: esys-particle
Version: 2.3.5+dfsg2-8
Severity: serious
Tags: ftbfs

Hi Maintainer

When built with Python 3.13 only, esys-particle builds successfully,
but then the resulting package does not seem to be functioning
correctly and the autopkgtests time out (see #946206).

Comparing the binary packages built with Python 3.13 as the default,
versus those built with Python 3.13 only:

$ debdiff -d esys-particle_2.3.5+dfsg2-8+b1_amd64.deb
esys-particle_2.3.5+dfsg2-8+b2_amd64.deb

Shows several files moved from:

/usr/lib/python3/dist-packages/esys/

to:

/usr/lib/python3.13/site-packages/esys/

Regards
Graham