Hi, I'm having trouble to register a repository plugin. In pants.ini I have the following setting :

[GLOBAL]
pants_version: 1.9.0
pythonpath: [
    '%(buildroot)s/pants-plugins',
  ]

backend_packages: [
     'foo'
  ]

in ./pants-plugins/foo/register.py

# . . .
def build_file_aliases():
  return BuildFileAliases(
    objects={
      'nexus': foo_repo,  
      'testing': testing_repo,
    },
  )