pg_dump bug in 9.4beta2 and HEAD

I'm seeing an assertion failure with "pg_dump -c --if-exists" which is
not ready to handle BLOBs it seems:

pg_dump: pg_backup_archiver.c:472: RestoreArchive: Assertion `mark !=
((void *)0)' failed.

To reproduce:

$ createdb test
$ pg_dump -c --if-exists test  (works, dumps empty database)
$ psql test -c "select lo_create(1);"
$ pg_dump -c --if-exists test  (fails, with the above mentioned assertion)