pg_upgrade vs user created range type extension

I have just encountered an apparent bug in pg_upgrade (or possibly pg_dump).


To recreate, install the cranges extension - which can be obtained via 
"git clone https://bitbucket.org/adunstan/pg-closed-ranges.git" - for 
both 9.4 and 9.5. Create a fresh 9.4 instance, create a database and in 
it run "create extension cranges schema pg_catalog". Then create a fresh 
9.5 instance and try to pg_upgrade from the 9.4 instance to the 9.5 
instance. Here's the tail of the log:

   pg_restore: creating SCHEMA "public"   pg_restore: creating COMMENT "SCHEMA "public""   pg_restore: creating
EXTENSION"cranges"   pg_restore: creating COMMENT "EXTENSION "cranges""   pg_restore: creating SHELL TYPE
"pg_catalog.cdaterange"  pg_restore: creating FUNCTION   "pg_catalog.cdaterange_canonical("cdaterange")"   pg_restore:
creatingTYPE "pg_catalog.cdaterange"   pg_restore: creating SHELL TYPE "pg_catalog.cint4range"   pg_restore: creating
FUNCTION  "pg_catalog.cint4range_canonical("cint4range")"   pg_restore: creating TYPE "pg_catalog.cint4range"
pg_restore:creating SHELL TYPE "pg_catalog.cint8range"   pg_restore: creating FUNCTION
"pg_catalog.cint8range_canonical("cint8range")"  pg_restore: creating TYPE "pg_catalog.cint8range"   pg_restore:
creatingFUNCTION "pg_catalog.cdaterange("date", "date")"   pg_restore: [archiver (db)] Error while PROCESSING TOC:
pg_restore:[archiver (db)] Error from TOC entry 191; 1255 16389   FUNCTION cdaterange("date", "date") andrew
pg_restore:[archiver (db)] could not execute query: ERROR: function   "cdaterange" already exists with same argument
types       Command was: CREATE FUNCTION "cdaterange"("date", "date")   RETURNS "cdaterange"        LANGUAGE "internal"
IMMUTABLE       AS $$range_construct...
 

The end result is that I currently can't upgrade a database using this 
extension, which is rather ugly.

Similar things happen if I put the extension in public instead of 
pg_catalog.

cheers

andrew