Improve ICU option handling in CREATE DATABASE
We check that the ICU locale is only specified if the ICU locale
provider is selected. But we did that too early. We need to wait
until we load the settings of the template database, since that could
also set what the locale provider is.
Reported-by: Marina Polyakova <m.polyakova@postgrespro.ru>
Discussion: https://www.postgresql.org/message-id/
9ba4cd1ea6ed6b7b15c0ff15e6f540cd@postgrespro.ru