Upgrade from 9.3 to 9.4 issue

I have just upgraded from Fedora 21 to 22.
This included an upgrade of PostgreSQL from 9.3 to 9.4 which causes postmaster
to fail because the existing databases are still at 9.3.
As suggested, I then ran postgresql-setup --upgrade but this failed with:

Performing Consistency Checks
-----------------------------
Checking cluster versions                                   ok
Checking database user is a superuser                       ok
Checking database connection settings                       ok
Checking for prepared transactions                          ok
Checking for reg* system OID user data types                ok
Checking for contrib/isn with bigint-passing mismatch       ok
Checking for invalid "line" user columns                    ok
Creating dump of global objects                             ok
Creating dump of database schemas
   books
   postgres
   pots
   stocks
   template1
                                                             ok

lc_collate cluster values do not match:  old "en_US.UTF-8", new "en_AU.UTF-8"
Failure, exiting

How can I recover from here?

Cheers and thanks,
Stephen Davies