Fix possible double import of cubes
For a new-style cube, if we import "cubicweb_<name>" and then import
"cubes.<name>", the cube will be imported twice. cubes.<name> and then
cubicweb_name is ok though...
When using pyramid, we try to find which cube define a "includeme" by importing
them with the name "cubes.<name>", so we (possibly ?) double import all new-style cube.
This case may also occur in tests with PyramidCWTest.
Touching the import loader to fix this scares me, so let's fix this by testing
"cubicweb_<name>" *before* "cubes.name" (for old style cubes, importing
cubicweb_<name> raise ImportError).
^build$
^dist$
\.egg-info$
^.tox$
^.cache$
\.pyc$
\.pyo$
\.bak$
\.old$
\~$
\#.*?\#$
\.swp$
^doc/book/en/apidoc$
\.old$
\.pybuild
cubicweb/server/test/data/slapd.conf
debian/python-cubicweb
debian/*.log
debian/*.substvars
debian/cubicweb-doc
debian/cubicweb
debian/files
syntax: regexp
.*/data.*/database/.*
.*/data/ldapdb/.*
.*/data/uicache/
.*/data/libpython/cubicweb_.*/i18n/.*\.po
^doc/html/
^doc/doctrees/
^doc/book/en/devweb/js_api/
^doc/_build
^doc/js_api/
test-results.xml