1. Create a database named "test" and "user" collection under it.
2. Enable sharding on test and shard test.user.
3. Create a database named "[^0-9]+" and "loc" collection under it.
4. Enable sharding on [^0-9]+.loc -> error message "can't have 2 databases that just differ on case have: test want to add: ^[0-9]" appears