Otherwise it fails downgrading, despite it is supposed to run everything
in the context of a transaction:
```
tests=# alter extension crankshaft update to '0.0.4';
ERROR: cannot drop function cdb_pyaggs(numeric[],numeric[]) because
other objects depend on it
DETAIL: extension crankshaft depends on function
cdb_pyaggs(numeric[],numeric[])
HINT: Use DROP ... CASCADE to drop the dependent objects too.
```
