Sorry Andreas, I hadn't seen your reply.
Ok, I see now that both plot-*properties.texi and genpropdoc.m are
distributed, which shouldn't happen as the latter is meant to build the
firsts.
I mainly followed images.mk example where both built images and the
original scripts (e.g. voronoi.eps and geometryimages.m) are distributed.
I think you are right that distributing .texi files should be enough, so
my last changeset should be backed out and I should remove genpropdoc.m
as a dependency for plot-*properties.texi.
A drawback is that modifying genpropdoc.m (which I hope will happen
often :-) won't trigger a rebuild of the doc any more.
What should I do?