dh_auto_install -a
   make[1]: Entering directory
   `/build/buildd-ocaml-gnuplot_0.8.3-2-armhf-MfThgI/ocaml-gnuplot-0.8.3'
   cp META.in META
   echo "version = \"0.8.3\"" >> META
   ocamlopt -inline 2 -c gnuplot_dir.ml
I believe the problem is that the intstall target has all as
prerequisite, which in turn depends on opt.
Bye,
Hendrik