upgrading ocaml requires rebuild of all ocaml packages. apparently this is because of the static linking between libraries.
to get the packages rebuilt in one run, special care must be taken to send the requests in certain order.
first ask someone with proper rights to remove current ocaml from builders
poldek -ev --noask ocaml ocaml-runtime
then start sending 
- ocaml
- ocaml-lablgl
- ocaml-lablgtk
- ocaml-findlib
- ocaml-postgres
- ocaml-mysql
- ocaml-pcre
- ocaml-equeue
- ocaml-net
- ocaml-xstr
- ocaml-wlex
- ocaml-netclient
- ocaml-stew
- ocaml-pxp
the rest of packages need to be rebuild can be queried with this command
$ ac-requires ocaml-runtime $ ac-requires ocaml