Global transaction does not work

[jayschwa]

For running all migrations in a global transaction, the README suggests code like the following:

var oldVersion, newVersion int64
err = db.RunInTransaction(func(tx *pg.Tx) error {
	oldVersion, newVersion, err = migrations.Run(tx, flag.Args()...)
	return err
})
if err != nil {
	panic(err)
}

After upgrading from v6.2.0 to v6.7.3, the code now fails:

BEGIN
SELECT count(*) FROM "pg_tables" WHERE (schemaname = 'public') AND (tablename = 'gopg_migrations')
SET idle_in_transaction_session_timeout = 0
LOCK TABLE gopg_migrations

		SELECT version FROM gopg_migrations ORDER BY id DESC LIMIT 1
	
COMMIT
panic: pg: transaction has already been committed or rolled back

I don't see nested transactions in the output, but it does look like the code will attempt to create a transaction for each migration: https://github.com/go-pg/migrations/blob/master/collection.go#L454