pg_upgrade --jobs

The pg_upgrade --jobs option is not passed as an argument when it calls pg_dump. I haven't found anything in docs or forums mentioning a reason for not supporting under certain circumstances other than possibly for pre-9.2. The pg_upgrade docs page states that it allows multiple CPUs to be used for dump and reload of schemas. Some databases I'm upgrading have 500,000+ tables and running with a single process is greatly increasing the upgrade time.

I am also using the --link option. 
I have tried "--jobs 20", "--jobs=20", placing this option first and last and many other variations.
I am upgrading 9.2.4 to 9.6.12 on CentOS 6.
Varying hardware but all with 32+ CPU cores.

su - postgres -c "/usr/pgsql-9.6/bin/pg_upgrade --jobs=20 --link \
       --old-bindir=/usr/pgsql-9.2/bin/ \
       --new-bindir=/usr/pgsql-9.6/bin/ \
       --old-datadir=/var/lib/pgsql/9.2/data/ \
       --new-datadir=/var/lib/pgsql/9.6/data/" 

I feel like there's a simple reason I've missed but this seems pretty straight forward. 
A secondary plan would be to find instructions for doing the same as "pg_upgrade --link" manually so I can run "pg_dump --jobs 20". 
Any assist is appreciated. 
Thanks,
S. Cervesa