z3 4.8.4

Error log

The package failed to build. The error log from opam follows.

Opam plugin "depext" may require upgrading/reinstalling. Reinstall the plugin on the current switch? [Y/n] y
The following actions will be performed:
  - recompile opam-depext 1.2.3

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-> retrieved opam-depext.1.2.3  (cached)
-> removed   opam-depext.1.2.3
-> installed opam-depext.1.2.3
Done.

<><> opam-depext.1.2.3 installed successfully <><><><><><><><><><><><><><><><><>
=> opam-depext is unnecessary when used with opam >= 2.1. Please use opam install directly instead
# Run eval $(opam env) to update the current shell environment

<><> Carrying on to "opam depext -viy z3.4.8.4 ocamlfind.1.9.6 num.1.5-1 host-arch-x86_64.1 conf-python-2-7.1.2 conf-gmp.4 conf-c++.1.0" 

Since version 2.1, opam now handles external dependencies alongside OCaml ones, and the `depext` plugin interface is provided for backwards compatibility only. Consider using your usual `opam install` command to install both OCaml and system dependencies, or `opam install <pkg> --depext-only` if you want to only install external dependencies.
# Detecting depexts using vars: arch=x86_64, os=linux, os-distribution=debian, os-family=debian
[ERROR] No solution for z3.4.8.4 & ocamlfind.1.9.6 & num.1.5-1 & host-arch-x86_64.1 & conf-python-2-7.1.2 & conf-gmp.4 & conf-c++.1.0:   * Missing dependency:
            - conf-python-2-7
            depends on the unavailable system package 'python2.7'. Use `--no-depexts' to attempt installation anyway, or it is possible that a depext package name in the opam file is incorrect.


Command failed: opam --cli=2.1 list --readonly --external '--resolve=z3.4.8.4,ocamlfind.1.9.6,num.1.5-1,host-arch-x86_64.1,conf-python-2-7.1.2,conf-gmp.4,conf-c++.1.0' --color=never returned 20