Re: psql \copy from sends a lot of packets

The following review has been posted through the commitfest application:
make installcheck-world:  tested, passed
Implements feature:       tested, passed
Spec compliant:           tested, passed
Documentation:            tested, passed

The patch was marked as the one that needs review and doesn't currently have
a reviewer, so I decided to take a look. The patch was tested on MacOS against
master `e0271d5f`. It works fine and doesn't seem to contradict the current
documentation.

The future COPY TO patch may require some changes in the docs, as Tom pointed
out. I also wonder if it may affect any 3rd party applications and if we care
about this, but I suggest we discuss this when and if a corresponding patch
will be proposed.

The new status of this patch is: Ready for Committer