more general solution

Author: Wayne Nilsen

sqlacodegen/codegen.py

@@ -497,8 +497,8 @@ def __init__(self, source_cls, target_cls, constraint, inflect_engine):
 class ManyToManyRelationship(Relationship):
     def __init__(self, source_cls, target_cls, assocation_table, inflect_engine):
         super(ManyToManyRelationship, self).__init__(source_cls, target_cls)
-
-        self.kwargs['secondary'] = repr(assocation_table.schema or 'dbo' + '.' + assocation_table.name)
+        prefix = assocation_table.schema + '.' if assocation_table.schema is not None else ''
+        self.kwargs['secondary'] = repr(prefix + assocation_table.name)
         constraints = [c for c in assocation_table.constraints if isinstance(c, ForeignKeyConstraint)]
         constraints.sort(key=_get_constraint_sort_key)
         colname = _get_column_names(constraints[1])[0]