[Python-Dev] Import hooks falling back on built-in import machinery?

[Georg Brandl]

While working on a patch involving sys.path_importer_cache, I discovered
that if a path_hooks import hook has been found for a given sys.path entry,
but isn't able to import a specific module, find_module() tries to import
the module from this sys.path entry as a regular file.

This results in e.g. doing an open call to /usr/lib/python25.zip/x.py when
I do "import x", while I think that once a sys.path entry has been identified
as belonging to a sys.path_hooks importer instance, it shouldn't be handled
by the built-in machinery anymore since the path string could be anything.

PEP 302 says "...it was chosen to ... simply fall back to the built-in logic
if no hook on sys.path_hooks could handle the path item", but that's
refering to sys.path entries, not individual module names to be imported.

Georg