[skeleton] do not import the __pkginfo__.py module to make cubes installable via setuptools When using a simple "import" statement, running 'python setup.py install' for a cube fails in a fresh virtualenv due to the fact the install of the dependencies (here cubicweb iteself) is done by the python process doing the cube's installation, so the __pkginfo__ module from the cube is already loaded (thus used) when installing cubicweb... So we apply the third technique from: https://packaging.python.org/en/latest/single_source_version.html

merge changes from 3.22.2

Added tag 3.22.2, debian/3.22.2-1, centos/3.22.2-1 for changeset 1b93ff37755b

[pkg] 3.22.2

[pkg] fix centos install

[datafeed] do NOT call commit in DataFeedXMLParser.process() (closes #10928592) and so, remove more useless code. Doing a commit in DataFeedXMLParser.process() is a bad idea because this method is called for every imported/updated entity, before handling deletions. So if we commit here, odds are quite high that we're violating some integrity constraint and end up with a ValidationError.

[schema] restore constraint checking when running on old sqlite Old sqlite3 doesn't provide CHECK constraint names in error messages, preventing us from translating a backend integrity error into a ValidationError. This was added in 2012, but the sqlite3 version in RHEL6 is older; so if we run on old sqlite, keep checking the constraints in python rather than only in SQL. Closes #10927494