db-statement-timeout is None
Problem description
When db-statement-timeout is not set, but postgres is used, the following error occurs
Initializing the system database
--------------------------------
Traceback (most recent call last):
File "/home/pchoffe/.virtualenvs/tuto/bin/cubicweb-ctl", line 8, in <module>
sys.exit(run())
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/cwctl.py", line 830, in run
CWCTL.run(args)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/logilab/common/clcommands.py", line 149, in run
sys.exit(command.main_run(args, rcfile))
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/logilab/common/clcommands.py", line 290, in main_run
self.run(args)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/serverctl.py", line 456, in run
CWCTL.run(['db-init', '--config-level',
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/logilab/common/clcommands.py", line 149, in run
sys.exit(command.main_run(args, rcfile))
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/logilab/common/clcommands.py", line 290, in main_run
self.run(args)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/serverctl.py", line 515, in run
init_repository(config, drop=self.config.drop)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/__init__.py", line 210, in init_repository
repo = Repository(config, vreg=vreg)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/repository.py", line 384, in __init__
self.system_source = self.get_source('native', 'system',
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/repository.py", line 512, in get_source
return sources.get_source(type, source_config, self, eid)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/sources/__init__.py", line 351, in get_source
return source_adapter(type)(repo, source_config, eid)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/logilab/common/modutils.py", line 125, in __call__
return self._getobj()(*args, **kwargs)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/sources/native.py", line 329, in __init__
SQLAdapterMixIn.__init__(self, source_config, repairing=repo.config.repairing)
File "/home/pchoffe/.virtualenvs/tuto/lib/python3.8/site-packages/cubicweb/server/sqlutils.py", line 316, in __init__
statement_timeout = int(source_config.get('db-statement-timeout', 0))
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'
la ligne correspondante dans le fichier sources
# sql statement timeout, in milliseconds (postgres only)
db-statement-timeout=
could this be related to the changes to recover configuration variables from the environment? 
Expected behaviour
source_config.get returns 0
Actual behaviour
db-statement-timeout is in sources_config variable and None
Installed version
CubicWeb 3.31.1