This is not public API and is not supposed to be used outside of catalog
tool.

Using getObject here is also wrong because it does not apply security
and does not check provided argument type.

To prevent retrieving too many documents, we usually pass limit=2 for
safety.

To detect inconsistencies, when only one result is expected we rely on
`brain, = portal_catalog(limit=2)` style unpacking to fail if more than
one result were found.