[opam] workaround opam ignoring the lock file with --locked
[opam] workaround opam ignoring the lock file with --locked

Summary:
This seems like a bug in opam, probably started after we moved the opam
files to opam/ in D27326495 (https://github.com/facebook/infer/commit/673c944fc3b1313d11a3735655bedd3d13aca992). I reported the strange behaviour in
https://github.com/ocaml/opam/issues/4313#issuecomment-853179145.

Reviewed By: rgrig

Differential Revision: D28837624

fbshipit-source-id: f91a58dbc

jvillard/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer