Weird failures on travis with 4.02.3

[pmetzger]

See, for example: https://travis-ci.com/ocaml-community/sedlex/jobs/213408755

but I've suddenly been getting the following errors during sedlex's CI runs with 4.02.3 but not any later version of OCaml:

<><> Gathering sources ><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
[ERROR] The sources of the following couldn't be obtained, aborting:
          - ocaml-base-compiler.4.02.3: Curl failed

[XVilka]

I think it's just a Travis network error, nothing related to the OCaml or Opam[-ci-scripts]. We (radareorg) see these problems often. Most probably because of their caching system (they cache http requests).

[pmetzger]

Travis has networking errors far too often. Frankly, Travis is not a very good CI system.

[XVilka]

Now it behaves much better, I think. Less network errors for a few months already. Probably can be closed now.

[pmetzger]

Perhaps. I think I'd like to encourage the community to use a different set of CI services in any case. The free version of Azure Pipelines has been working quite well for Macports.