bob_dbmanage.py breaks when one of the dbs are broken

Here is what I faced today:

Traceback (most recent call last):
  File "bin/bob_dbmanage.py", line 85, in <module>
    sys.exit(bob.db.base.script.dbmanage.main())
  File "src/bob.db.base/bob/db/base/script/dbmanage.py", line 24, in main
    formatter_class=RawDescriptionHelpFormatter)
  File "src/bob.db.base/bob/db/base/manage.py", line 185, in create_parser
    driver.add_commands(subparsers)
  File "src/bob.db.swan/bob/db/swan/driver.py", line 153, in add_commands
    from .create import create_subparser
  File "src/bob.db.swan/bob/db/swan/create.py", line 8, in <module>
    from .common import swan_bio_file_metadata
ImportError: cannot import name 'swan_bio_file_metadata'

This kind of errors should be handled.