Bug#907042: opam 1.2.0 is deprecated (jessie)

[rjbou <raja.boujbel@ocamlpro.com>]

Package: opam
Version: 1.2.0-1+deb8u1
Severity: grave
Justification: renders package unusable
Tags: jessie

Dear Maintainer,

On jessie, opam 1.2.0 is packaged but it is officially deprecated since
a year [1][2].

It makes opam unusable for jessie users: already initialised ones can't
install new compilers nor update packages, and with a fresh install opam
is almost unusable (e.g. [3]).

The solution is to upgrade the opam package to 1.2.2.

[1] https://opam.ocaml.org/blog/deprecating-opam-1-2-0
[2] https://discuss.ocaml.org/t/rfc-deprecating-opam-1-2-0/332
[3] https://github.com/astrada/google-drive-ocamlfuse/issues/324

Note: I talked with a maintainer who advised me to set severity to
grave.

------------------------------------
Versions of packages opam depends on:
ii  build-essential  12.3
ii  curl             7.52.1-5+deb9u6
ii  libbz2-1.0       1.0.6-8.1
ii  libc6            2.24-11+deb9u3
pn  opam-docs        <none>
ii  tar              1.29b-1.1
ii  unzip            6.0-21
ii  wget             1.18-5+deb9u2
ii  zlib1g           1:1.2.8.dfsg-5

Versions of packages opam recommends:
ii  aspcud     1:1.9.1-2+b1
pn  darcs      <none>
ii  git        1:2.11.0-3+deb9u3
ii  mercurial  4.0-1+deb9u1
ii  ocaml      4.02.3-9
ii  rsync      3.1.2-1+deb9u1

opam suggests no packages.