postgres 9.6.8 to 10 on Ubuntu 16.04.4 LTS --- tsearch2 unloadable...

I get that this library is no longer need. It's blowing up my upgrade to
10. Output:

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

Then, in the text file:

could not load library "$libdir/tsearch2": ERROR: could not access file
"$libdir/tsearch2": No such file or directory

But I can't see how or where this library is still installed. Running \dx
on my database:

Name | Version | Schema |
Description
---------------+---------+------------+---------------------------------------------------------------------
adminpack | 1.0 | pg_catalog | administrative functions for
PostgreSQL
btree_gist | 1.2 | public | support for indexing common
datatypes in GiST
cube | 1.2 | public | data type for multidimensional cubes
earthdistance | 1.1 | public | calculate great-circle distances on
the surface of the Earth
hstore | 1.4 | public | data type for storing sets of (key,
value) pairs
intarray | 1.2 | public | functions, operators, and index
support for 1-D arrays of integers
pgcrypto | 1.3 | public | cryptographic functions
plpgsql | 1.0 | pg_catalog | PL/pgSQL procedural language
plpythonu | 1.0 | pg_catalog | PL/PythonU untrusted procedural
language
postgis | 2.4.3 | public | PostGIS geometry, geography, and
raster spatial types and functions
(10 rows)

No tsearch2. I can't for the life of me figure out how to remove this so I
can upgrade to 10. Any tips?

--
Wells Oliver
wells(dot)oliver(at)gmail(dot)com <wellsoliver(at)gmail(dot)com>