merge 3.20.9 into 3.21 Fix conflict in unittest_postgres.py by changing sources configuration in PostgresTimeoutConfiguration.__init__ so it happens *after* setUpModule().

version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
http://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))