help needed with error during upgrade (9.4 -> 9.5)

hello list,

i wonder if anyone can give me a helping hand with the issue i am
experiencing during an attempted to upgrade from postgres 9.4 to 9.5.

the steps i took so far (on my archlinux system):
- first i upgraded postgresql and postgresql-libs (from 9.4.5 to 9.5.1)
- followed steps described at
https://wiki.archlinux.org/index.php/PostgreSQL#Quick_guide
- pg_upgrade terminated with the following error:
Could not load library "$libdir/postgis-2.2"
ERROR: incompatible library "/usr/lib/postgresql/postgis-2.2.so": version
mismatch
DETAIL: Server is version 9.5, library is version 9.4.
- i upgraded postgis from 2.2.0 to 2.2.1 and ran pg_upgrade again.

this time it ended with a different error but now i am unable to proceed
any further (no idea which way to take it from here):
..
Checking for presence of required libraries fatal

Your installation references loadable libraries that are missing from the
new installation. You can add these libraries to the new installation,
or remove the functions using them from the old installation. A list of
problem libraries is in the file:
loadable_libraries.txt

Failure, exiting
$ cat loadable_libraries.txt
Could not load library "$libdir/postgis-2.2"
ERROR: attempt to redefine parameter "postgis.backend"

oddly enough i can see postgis-2.2 in both 9.4 and the new installation:
/opt/pgsql-9.4/lib/postgis-2.2.so
/usr/lib/postgresql/postgis-2.2.so

any help or advice is welcome.

thank you, jose