When using SET search_path the schemas must not be enclosed in single quotes
as otherwise the list of schemas will be treated as a single schema name instead.

Erroneous example:

```
SET search_path TO 'pg_catalog, temp';
```

Setting the search_path this way will result in the actual search_path being
pg_temp, pg_catalog, "pg_catalog, pg_temp" instead of the intended value of
pg_catalog, pg_temp. This would allow shadowing catalog relations with relations
in the pg_temp schema.