Debian packaging driver crashes on sid, without ID_VERSION

On Debian sid, our packaging driver misbehaves:

python3 manage.py packaging
CRITICAL plainbox.crashes: Executable 'manage.py' invoked with Namespace(command=<plainbox.provider_manager.PackagingCommand object at 0x7fa10e173518>, debug_console=False, debug_interrupt=False, log_level=None, pdb=False, trace=[]) has crashed
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/plainbox/impl/clitools.py", line 560, in dispatch_and_catch_exceptions
    return self.dispatch_command(ns)
  File "/usr/lib/python3/dist-packages/plainbox/impl/clitools.py", line 556, in dispatch_command
    return ns.command.invoked(ns)
  File "/usr/lib/python3/dist-packages/plainbox/provider_manager.py", line 1295, in invoked
    driver.inspect_provider(provider)
  File "/usr/lib/python3/dist-packages/plainbox/impl/unit/packaging.py", line 260, in inspect_provider
    if self.is_applicable(unit):
  File "/usr/lib/python3/dist-packages/plainbox/impl/unit/packaging.py", line 250, in is_applicable
    if (not _strategy_id_version(unit, os_release)
  File "/usr/lib/python3/dist-packages/plainbox/impl/unit/packaging.py", line 224, in _strategy_id_version
    and unit.os_version_id == os_release['VERSION_ID'])
KeyError: 'VERSION_ID'

This is caused by the lack of VERSION_ID field in /etc/os-release.