Extensions not dumped when --schema is used

Hello,

I've discovered something today that I didn't really expect. When a user
dumps a database with the --schema flag of pg_dump, extensions in this
schema aren't dumped. As far as I can tell, the documentation isn't clear
about this ("Dump only schemas matching pattern; this selects both the
schema itself, and all its contained objects."), though the source code
definitely is ("We dump all user-added extensions by default, or none of
them if include_everything is false (i.e., a --schema or --table switch was
given).", in pg_dump.c).

I was wondering the reason behind this choice. If anyone knows, I'd be
happy to hear about it.

I see two things:
* it's been overlooked, and we should dump all the extensions available in
a schema if this schema has been selected through the --schema flag.
* it's kind of like the large objects handling, and I'd pretty interested
in adding a --extensions (as the same way there is a --blobs flag).

Thanks.

Regards.

--
Guillaume.