And just a few minutes ago, we finally merged that PR.
In case you’re in trouble (esp. on macOS I guess since there a gpatch is available which has file descriptor leaks), what you can do is get the latest opam 2.4.0 beta1 (from Release 2.4.0~beta1 · ocaml/opam · GitHub) which includes a patch written in OCaml without file descriptor leaks.
Later there will be subsequent runs of the same utility, archiving more packages.