[source synchronization hooks] Fix/enhance system source hooks
They are broken if launched during repository initialization (this was not the
case yet, but will be soon...). Add additional checks to ensure one doesn't try
to store system source config in the database, as it will be ignored in favor of
the "sources" file.
include README
include COPYING
include COPYING.LESSER
include pylintrc
include bin/cubicweb-*
include man/cubicweb-ctl.1
recursive-include doc README makefile *.conf *.js *.css *.py *.rst *.txt *.html *.png *.svg *.zargo *.dia
recursive-include misc *.py *.png *.display
include web/views/*.pt
recursive-include web/data external_resources *.js *.css *.py *.png *.gif *.ico *.ttf
recursive-include web/wdoc *.rst *.png *.xml ChangeLog*
recursive-include devtools/data *.js *.css *.sh
recursive-include i18n *.pot *.po
recursive-include schemas *.py *.sql
recursive-include test/data bootstrap_cubes *.py *.sql
recursive-include entities/test/data bootstrap_cubes *.py
recursive-include sobjects/test/data bootstrap_cubes *.py
recursive-include hooks/test/data bootstrap_cubes *.py
recursive-include server/test/data bootstrap_cubes *.py source* *.conf.in *.ldif
recursive-include devtools/test/data bootstrap_cubes *.py *.txt *.js
recursive-include web/test/data bootstrap_cubes pouet.css *.py
recursive-include web/test/jstests *.js *.html *.css *.json
recursive-include web/test/windmill *.py
recursive-include skeleton *.py *.css *.js *.po compat *.in *.tmpl
prune doc/book/en/.static
prune doc/book/fr/.static
prune doc/html/_sources/
prune misc/cwfs
prune goa