pyxplot does not show anything with gv viewer

Binary package hint: pyxplot

Using pyxplot 0.8.1 out of the box, if you ask for a plot, nothing is shown.

pyxplot> plot sin(x) # nothing happens

The viewer is set to default (gv):

pyxplot> show viewer
Settings which have not been changed by the user are shown in green.
Settings which have been changed by the user are shown in amber.

set viewer auto # Selects the postscript viewer used by the X11 terminals (gv).

...and gv is installed:

(0)pern:~/software/bugs/pyxplot% wajig status gv
Package Installed Previous Now State
=======================-===============-===============-===============-=====
gv 1:3.7.1-1 1:3.7.1-1 1:3.7.1-1 install

If I set the viewer to evince, or manually set the viewer to gv, (with set viewer evince or set viewer gv), it works. I checked, I have no .pyxplotrc files around.