Please find attached a patch to provide some basic ordering to the system views pg_available_extensions and pg_available_extension_versions. It is sorely tempting to add ORDER BYs to many of the other views in that file, but I understand that would be contentious as there are reasons for not adding an ORDER BY. However, in the case of pg_available_extensions, it's a very, very small resultset, with an obvious default ordering, and extremely unlikely to be a part of a larger complex query. It's much more likely people like myself are just doing a "SELECT * FROM pg_available_extensions" and then get annoyed at the random ordering.
Cheers,
Greg