Fix crash at the end of 'opam update'
Fix crash at the end of 'opam update'

Not sure why, but Dose's `edos_coinstall` was crashing during the call
to `check_for_conflicts`. Extracting installed packages from the cudf
universe rather than re-converting them seems to fix it.

I was getting:

    (W)CudfAdd: package ocp-build (= 7) is not associate with an integer in the given universe
    Fatal error:
    Not_found

abate/opam,abate/opam