BUG #4664: \o does not allow successive output to be appended

The following bug has been logged online:

Bug reference: 4664
Logged by: Brent Wood
Email address: pcreso@pcreso.com
PostgreSQL version: 8.1.16
Operating system: SLES, OpenSuse
Description: \o does not allow successive output to be appended
Details:

The \o command to capture output to a fike will overwrite any existing file.
I have users here wishing to accumulate \o output in a file. Perhaps a \o+
option could be provided to allow successive output to be appended to the
same file?

Tom Lane suggested \o | cat >> file as a workaround.

I know this is not a bug, but I couldn't find anywhere to submit a wishlist
item, only pages listing existing items.