solver not getting right package

[avsm]

It's Friday, so here's a constraint solver bug :) I just tried to install github and got a bunch of downgrades. Explicitly requesting the latest version github.0.4.3 made it succeed. The heuristics should really favour the latest version, shouldnt they?

This will come up a lot with the frequent Core upgrades, sadly...

$ opam install github
. brute-force exploration timed-out [721 states, 5s].
You might need to add explicit version constraints to your request to get a better answer.
The following actions will be performed:
 - remove shared-memory-ring.0.3.0
 - remove comparelib.109.13.00
 - remove ocplib-endian.0.2
 - remove herelib.109.13.00
 - remove optcomp.1.4
 - install cppo.0.9.3 [required by github]
 - downgrade ocamlfind.1.3.3 to 1.3.2 [required by cow, github, xmlm]
 - recompile camomile.0.8.3 [use ocamlfind]
 - recompile cmdliner.0.9.2 [use ocamlfind]
 - downgrade cstruct.0.7.1 to 0.5.3 [required by github]
 - install easy-format.1.0.1 [required by github]
 - install menhir.20120123 [required by github]
 - recompile ounit.1.1.2 [use ocamlfind]
 - downgrade re.1.2.0 to 1.1.0 [required by cow, github]
 - recompile react.0.9.4 [use ocamlfind]
 - recompile res.3.2.0 [use ocamlfind]
 - install ssl.0.4.6 [required by github]
 - downgrade type_conv.109.13.00 to 108.00.02 [required by cow, github]
 - recompile ulex.1.1 [use ocamlfind]
 - downgrade xmlm.1.1.1 to 1.1.0
 - recompile mirari.0.9.1 [use ocamlfind]
 - install biniou.1.0.5 [required by github]
 - install atd.1.0.2 [required by github]
 - downgrade uri.1.3.6 to 1.1 [required by github]
 - recompile zed.1.2 [use ocamlfind]
 - recompile lwt.2.4.3 [use ocamlfind]
 - downgrade bin_prot.109.13.00 to 108.00.02 [required by github]
 - downgrade dyntype.0.9.0 to 0.8.3 [required by cow]
 - downgrade fieldslib.109.13.00 to 108.00.02 [required by github]
 - downgrade pa_ounit.109.13.00 to 108.00.02 [required by github]
 - downgrade pipebang.109.13.00 to 108.00.02 [required by github]
 - downgrade sexplib.109.13.00 to 108.00.02 [required by github]
 - downgrade variantslib.109.13.00 to 108.00.02 [required by github]
 - install yojson.1.1.3 [required by github]
 - recompile lambda-term.1.2 [use ocamlfind]
 - downgrade xenstore.1.2.0 to 1.0.0 [required by github]
 - downgrade cow.0.5.3 to 0.3.2
 - downgrade core.109.13.00 to 108.00.02 [required by github]
 - install atdgen.1.2.2 [required by github]
 - recompile utop.1.4.0 [use ocamlfind]
 - downgrade mirage.0.8.0 to 0.5.0 [required by github]
 - downgrade async_core.109.13.00 to 108.00.02 [required by github]
 - downgrade mirage-net.0.5.2 to 0.3.1 [required by github]
 - downgrade async_unix.109.13.00 to 108.00.02 [required by github]
 - downgrade async_extra.109.13.00 to 108.00.02 [required by github]
 - downgrade async.109.13.00 to 108.00.02 [required by github]
 - install cohttp.0.9.1 [required by github]
 - install github.0.3.0
10 to install | 11 to reinstall | 0 to upgrade | 22 to downgrade | 5 to remove
Do you want to continue ? [Y/n] ^C'opam install github' failed.

$ opam install github.0.4.3
The following actions will be performed:
 - install cppo.0.9.3 [required by github]
 - install easy-format.1.0.1 [required by github]
 - upgrade ocplib-endian.0.2 to 0.3 [required by github]
 - upgrade type_conv.109.13.00 to 109.14.00 [required by github]
 - upgrade pipebang.109.13.00 to 109.14.00 [required by github]
 - install menhir.20120123 [required by github]
 - upgrade herelib.109.13.00 to 109.14.00 [required by github]
 - install ssl.0.4.6 [required by github]
 - install biniou.1.0.5 [required by github]
 - upgrade bin_prot.109.13.00 to 109.14.00 [required by github]
 - upgrade comparelib.109.13.00 to 109.14.00 [required by github]
 - recompile dyntype.0.9.0 [use type_conv]
 - upgrade fieldslib.109.13.00 to 109.14.00 [required by github]
 - upgrade pa_ounit.109.13.00 to 109.14.00 [required by github]
 - upgrade sexplib.109.13.00 to 109.14.00 [required by github]
 - upgrade variantslib.109.13.00 to 109.14.00 [required by github]
 - install atd.1.0.2 [required by github]
 - recompile lwt.2.4.3 [use ssl]
 - install yojson.1.1.3 [required by github]
 - recompile cow.0.5.3 [use type_conv]
 - upgrade core.109.13.00 to 109.14.00 [required by github]
 - recompile lambda-term.1.2 [use ssl]
 - install atdgen.1.2.3 [required by github]
 - upgrade async_core.109.13.00 to 109.14.00 [required by github]
 - recompile utop.1.4.0 [use ssl]
 - upgrade async_unix.109.13.00 to 109.14.00 [required by github]
 - upgrade async_extra.109.13.00 to 109.14.00 [required by github]
 - upgrade async.109.13.00 to 109.14.00 [required by github]
 - recompile cstruct.0.7.1 [use herelib, ocplib-endian, pipebang, ssl, type_conv]
 - upgrade shared-memory-ring.0.3.0 to 0.3.1 [required by github]
 - upgrade xenstore.1.2.0 to 1.2.1 [required by github]
 - recompile mirage.0.8.0 [use herelib, ocplib-endian, pipebang, ssl, type_conv]
 - recompile mirage-net.0.5.2 [use herelib, ocplib-endian, pipebang, ssl, type_conv]
 - install cohttp.0.9.6 [required by github]
 - install github.0.4.3
10 to install | 8 to reinstall | 17 to upgrade | 0 to downgrade | 0 to remove
Do you want to continue ? [Y/n] ^C'opam install github.0.4.3' failed.

Cloned from OCamlPro/opam-repository#554

[samoht]

This should be fixed.