Reproducible: always.

To reproduce : create an arbitrary tetx file containing a ~ symbol and run a2ps
on it with -X koi8-r option.

Expected: some ~-like symbol in the output
Actual: empty space instead of it.

As far as I understand it, the problem comes from the fact that
/usr/share/a2ps/encoding/koi8.edf specify using "tilde" for ~ while the fonts
that are used for Cyrillics output only have "asciitilde", but no "tilde". And
indeed, replacing "tilde" with "asciitilde" in koi8.edf solves the problem,
although I have no idea whether this is a reasonable solution or an ugly hack...