There is an install_on_linux function https://github.com/ocaml/ocaml-ci-scripts/blob/master/.travis-ocaml.sh#L84
It sets env variables like OCAML_VERSION and OCAML_FULL_VERSION AFTER calling apt-get install ocaml ocaml-base ..., i.e. after call of install_ppa, while in the previous version it was done BEFORE, so actually apt-get install worked before with updated env, e.g. full_apt_version ocaml was expanded to ocaml=4.02.3-2ppa4~trusty, because OCAML_VERSION was set to 4.02.3.
In other words, a user-defined OCAML_VERSION is used for building now, not for tests only, while it wasn't so before last changes.
So a question - Is it correct? In our case, it breaks lot's of stuff, because we do build for many versions of ocaml.And previously it worked well just because the user-defined version was used for tests only, but not for building.
Thanks!