This looks like a problem with the dependency computation algorithm.
If you have not installed an external CUDF solver such as aspcud
(which does a better job than the internal solver of OPAM), it may
solve such spurious dependency issues.
  https://opam.ocaml.org/doc/Specifying_Solver_Preferences.html

(Or use the remove server farm
http://cudf-solvers.irill.org/index.html if you don't want to install
an external solver and don't mind your install requests to be sent
over the network)

On Sat, Jul 18, 2015 at 9:36 PM, Kenneth Adam Miller
<kennethadammiller@gmail.com> wrote:
> There are duplicate ocamlfind specific opam packages:
>
> opam search ocamlfind
> ...
> ocamlfind-ocj             --  A library manager for OCaml
> ocj-ocamlfind             --  A library manager for OCaml
>
>
>
> In a second note, I have to install the library base-bytes. ocamlfind
> 1.5.5-ocp is required by base-bytes, when a non-ocp install of ocamlfind was
> working fine. ocamlfind 1.5.5-ocp blows up with the following errors:
>
> #=== ERROR while installing ocamlfind.1.5.5+ocp1
> ==============================#
> # opam-version 1.2.0
> # os           linux
> # command      make all
> # path
> /home/kennethadammiller/.opam/ocamljava-2.0-alpha3/build/ocamlfind.1.5.5+ocp1
> # compiler     ocamljava-2.0-alpha3
> # exit-code    2
> # env-file
> /home/kennethadammiller/.opam/ocamljava-2.0-alpha3/build/ocamlfind.1.5.5+ocp1/ocamlfind-12342-e7966f.env
> # stdout-file
> /home/kennethadammiller/.opam/ocamljava-2.0-alpha3/build/ocamlfind.1.5.5+ocp1/ocamlfind-12342-e7966f.out
> # stderr-file
> /home/kennethadammiller/.opam/ocamljava-2.0-alpha3/build/ocamlfind.1.5.5+ocp1/ocamlfind-12342-e7966f.err
> ### stdout ###
> # ...[truncated]
> #           ocaml_args.cmo frontend.cmo
> # if [ "false" = "true" ]; then                 \

> # cp topfind.ml.in topfind.ml;                             \
> # else                                                             \
> # sed -e '/PPXOPT_BEGIN/,/PPXOPT_END/ d' topfind.ml.in     \
> # > topfind.ml ;                                   \
> # fi
> # ocamlc -I +compiler-libs -c topfind.mli
> # ocamlc -I +compiler-libs -g -c topfind.ml
> # make[1]: Leaving directory
> `/home/kennethadammiller/.opam/ocamljava-2.0-alpha3/build/ocamlfind.1.5.5+ocp1/src/findlib'
> ### stderr ###
> # File "itest-aux/ppx.ml", line 1, characters 0-25:
> # Error: Unbound value Toploop.preprocess_phrase
> # Makefile:160: depend: No such file or directory
> # File "topfind.ml", line 1:

> # Error: The files
> /home/kennethadammiller/.opam/ocamljava-2.0-alpha3/lib/ocaml/compiler-libs/toploop.cmi
> #        and
> /home/kennethadammiller/.opam/ocamljava-2.0-alpha3/lib/ocaml/compiler-libs/parsetree.cmi
> #        make inconsistent assumptions over interface Warnings
> # make[1]: *** [topfind.cmo] Error 2
> # make: *** [all] Error 2
>
>
> =-=- Error report
> -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> The following failed
>  - install   ocamlfind.1.5.5+ocp1
> Due to the errors, the following have been cancelled
>  - install   base-bytes.base