More probs with BLOBs

We are getting a strange thing happening if the lo_export(attr, path)
destination is a fifo.

First, in the normal case, there is output to the file but also
feedback to stdout (or somewhere, appearing on the VT screen) of the
number 1.

-----------
         1
(1 row)

Now, if the destination file is a fifo and a psql -c command is given
from the shell to lo_export(attr, '/path/to/fifo') we don't get that
feedback, but then a cat of the fifo to a normal file (cat fifo >
file) writes the BLOB content to the destination file but also sends

-----------
         1
(1 row)

(or just "1" with psql -t) to the console, apparently (not stderr).

So it seems to us that the lo_export output can't be piped (via a
named pipe) to another process that reads from the pipe and expects
the valid BLOB contents.

Beyond my understanding.  What is happening here, and can the echoing
to the fifo be avoided?  Ideas, anyone?

(PostgreSQL 9.1.2, Linux 2.6.29.)

Elle