Remove redundant DROP FUNCTIONs

[robins]

Upgrading extension from v1.1.0 to v1.2.0 fails.

The error is owing to multiple DROP FUNCTION calls with similar signature. The script would have succeeded if they were DROP FUNCTION IF EXISTS, but that seems unnecessary here.

postgres=# create extension pgtap version '1.1.0';
CREATE EXTENSION
postgres=# \dx
                 List of installed extensions
  Name   | Version |   Schema   |         Description
---------+---------+------------+------------------------------
 pgtap   | 1.1.0   | public     | Unit testing for PostgreSQL
 plpgsql | 1.0     | pg_catalog | PL/pgSQL procedural language
(2 rows)

postgres=# select * from pg_available_extension_versions where name = 'pgtap';
 name  | version | installed | superuser | trusted | relocatable | schema | requires  |           comment
-------+---------+-----------+-----------+---------+-------------+--------+-----------+-----------------------------
 pgtap | 1.1.0   | t         | f         | f       | t           |        | {plpgsql} | Unit testing for PostgreSQL
 pgtap | 1.2.0   | f         | f         | f       | t           |        | {plpgsql} | Unit testing for PostgreSQL
 pgtap | 1.2.1   | f         | f         | f       | t           |        | {plpgsql} | Unit testing for PostgreSQL
(3 rows)

postgres=# alter extension pgtap update to '1.2.0';
ERROR:  function _agg(name) does not exist

[theory]

🤦🏻 Nice find, thank you!