cubicweb #799884 do not attempt to load stuff with incorrect names which sit in cubes/ [resolved]

Currently, if a directory with a name invalid for a Python module lives in the cubes package directory, a load attempt is made which fails with a possibly difficult to interpret error message.

Case at hand, a cube directory mycube was renamed to mycube.bak, cubicweb-ctl will exit with:

ImportError: No module named bak

Proposed fix: match the contents of cubes/ with what is a valid Python identifier [_a-zA-Z][_a-zA-Z0-9]*, warn if something which does not match is found and skip.

done in3.8.0
load left0.000
closed by<not specified>