*: keep using func_code and not yet __code__ with scripts
On Zope2, python scripts do not have __code__, they only have
func_code (and same for __defauls__/func_defaults).
We tried to backport the support of __code__ from Zope4 as a Zope2
patch - it was SlapOS patch slapos@4fa33dfc -
but this patch was incomplete. We tried to backport more, but then
realized that we don't need to use __code__ on ERP5 master yet,
because ERP5 master branch is still supporting Zope2 only.
This patch revert a small part of a17bb910 (py2/py3: Make Products
code compatible with both python2 and python3., 2022-04-13), the part
where we use f.__code__ where f might be a python script. For now,
we'll apply this patch only on the Zope4 branch.
A few places where f.__code__ was used and f was a for sure not a
python script but a simple class method or function are kept here, as
__code__ support is missing only on in ZODB scripts.