Fix AttributeError on postcommit when db-create adds non-system CWSource entities In this case, `Repository.add_source` is called from an operation, not from `Repository.init_sources_from_database`, thus the attribute `sources_by_eid` does not exist. Closes #16251078.

[devctl] Optimize cleanup_sys_modules a bit by moving out of a loop a costly computation that is constant. This at least benefits the `i18ncube` command. Related to #15789486.

[pyramid] Install file listing monitored files in application home Instead of using a temporary file, that never gets deleted. Closes #16159807.

[pyramid] Fix login error message language Use http negotiation unless language is explicitly set for the site. Closes #16236485.

i18n update Pyramid-related messages were not translated. Closes #16236243.

[pyramid] Add action verb used in some messages displayed by the command For instance we'll see 'instance started' instead of 'instance None', which is nicer.

[pyramid] No more need to check CW version since it's now shipped with it

[pyramid] Fix 404 handling Avoid seeing a traceback in the UI by catching it before it reaches pyramid and restore usage of the '404' view. Closes #16159863

Fix broken flake8 configuration and flake8 errors which were hidden by this breakage. flake8 --filename options doesn't work as expected: * it's expected to be a shell pattern, using stdlib's fnmatch.fnmatch function internally. This funciton thinks that 'cubicweb/x.py' doesn't match 'cubicweb/x.py' (there must be a reason but that's not the point), hence no file was actually checked ; * as this is a list of pattern, each encountered file is checked against each pattern, leading to run time explosion. So maintain list of files to check in a separated file and give this list to flake8 using unix's xarg command.

[entities] Fix typo in wfobjs debug message