debian: T9261: warn when byte-compilation fails instead of hiding it

The compileall call for the XML reference cache ended in '|| true', so a real
failure left no trace at all. Report it on stderr instead, and give py3compile
the same treatment so the two adjacent calls behave alike.

Deliberately not fatal. Bytecode is an optimisation: if it cannot be built the
CLI is slower but entirely correct, so aborting the installation - and with it
any image build - would be a worse outcome than a slow shell. This postinst has
no 'set -e' and contains no exit statements, so a failing command here has never
been treated as fatal; adding one now would make byte-compilation the single
exception in the file.

Note that compileall exits 0 for a missing directory and only returns nonzero on
an actual compilation error, so the warning fires on the case worth knowing
about and stays quiet otherwise.

0 files changed, 0 insertions, 0 deletions