some historic distfiles with wrong checksums in opam

[avsm]

Building /home/opam/opam-repository/archives/gen.0.2+opam.tar.gz
[gen.0.2] Downloading https://github.com/c-cube/gen/archive/0.2.tar.gz
[ERROR] Wrong checksum for /tmp/opam-41-d6d332/0.2.tar.gz:
  - 71df6f679f051a59e1c7d3fe71ed427d [expected result]
  - 4630f81c67531d217e9328eff9f3a11b [actual result]
This is surely due to outdated package descriptions and should be fixed by running `opam update`.
In case an update does not fix that problem, you can use the `--no-checksums` command-line option
to /bypass checking for invalid checksums.

[c-cube]

Yes, I messed up with versions a while ago. Is it really bad? The version is old enough I can safely remove it from opam, if needed.

[avsm]

Either fixing it or removing it is fine by me -- fixing the checksum preferred so that the OPAM history is available for mining.

[c-cube]

That should be fixed.