python3.9+ should be compiled with --with-tzpath option

[Paul G]

PEP 615 added a compile-time option for specifying the location of time zone data, with a primary use case being that it would allow distros to specify where the system-deployed zoneinfo files are.

See https://www.python.org/dev/peps/pep-0615/#compile-time-options and https://docs.python.org/3/library/zoneinfo.html#zoneinfo-data-compile-time-config

Since debian's tzdata is always deployed to /usr/share/zoneinfo, it would be a good idea to compile with --with-tzpath=/usr/share/zoneinfo, so that the default zoneinfo.TZPATH (i.e. the value when the time zone search path is not modified by an environment variable or zoneinfo.reset_tzpath) is ('/usr/share/zoneinfo',) rather than:

('/usr/share/zoneinfo',
'/usr/lib/zoneinfo',
'/usr/share/lib/zoneinfo',
'/etc/zoneinfo')

This will mostly make failed lookups faster, and possibly avoid some bugs that would be hit by users who have some old non-system time zones distributed to one of the other locations.