Tsearch2 removal bit me - how to correct?

Attempting to migrate to 10.0 from 9.6, which has had "tsearch2" loaded
for backward compatibility since "forever" (which I suspect is no longer
really required as the capability is internal and has been for a long
time) results in this blowup logged in loadable_libraries.txt:

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

The server log says:

2017-10-15 10:14:58.593 CDT [86864] ERROR:  could not access file
"$libdir/tsearch2": No such file or directory
2017-10-15 10:14:58.593 CDT [86864] STATEMENT:  LOAD '$libdir/tsearch2'

Which is true, incidentally.

The problem is that I can't find any databases under the old database
collection that have the extension loaded any longer (checking all of
them don't show any with it in; I removed a few old databases that were
no longer needed and DID have it, along with the tsearch2() function
itself in a few more), so I don't know what to drop in order to clear
this, and it's blocking an attempt to upgrade to 10.0.

So what's causing this to be requested on startup and how do I kill it? 
There doesn't appear to be an obvious way to deinstall it from the 9.6
cluster....

--

Karl Denninger
karl(at)denninger(dot)net <mailto:karl(at)denninger(dot)net>
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