reproducible 9.5: ERROR: requested object address for unsupported object class 32: ...

Hi all,

Attached is a small testcase which should produce an ERROR like:

ERROR:  requested object address for unsupported object class 32: text
result "unrecognized object 3576 112581 0"

Tested on git master.

Some further tidbits: object class 32 corresponds to OCLASS_TRANSFORM
by my reckoning, which lines up with the ERROR happening during
dropping the  hstore_plpython2u extension, which contains some
transforms.

I happened upon this case by digging around in the event trigger
handling of transforms after perusing the scan-build complaint[1]
about the T_CreateTransformStmt case on line 1440 of
src/backend/tcop/utility.c neglecting to set 'address', then passing
that struct on to EventTriggerCollectSimpleCommand. Not sure if that's
precisely related to what's happening here, since the error here seems
to only happen during the DROP EXTENSION, not CREATE, but that area of
the code sure smells funny to me.

Josh

[1] http://pgci.eisentraut.org/jenkins/view/PostgreSQL/job/postgresql_master_scan-build/2285/clangScanBuildBugs/browse/report-GQoirj.html#EndPath