Invalid_argument("OpamEnv.unzip_to") opam error after installing conf-openblas

[pklehre]

The following sequence of commands on a fresh opam init (opam v2.1.3) leads to an error that renders the opam switch in an unusable state (e.g., impossible to install new packages)

opam switch create 5.1.1+flambda ocaml-variants.5.1.1+options ocaml-option-flambda
opam install conf-openblas

Error:

[pkl@zeta ~]$ opam env
Fatal error:
Invalid_argument("OpamEnv.unzip_to")

[mseri]

I see, I think it is due to a bug in opam < 2.1.5:

2.1.5:
* [BUG] Variables are now expanded in build-env (as for setenv) [#5352 @dra27]
* Correctly handle empty environment variable additions [#5350 @dra27]
* Skip empty environment variable additions [#5350 @dra27]
[…]

[mseri]

Ping @dra27, what do you suggest to keep openblas installable? I think we should probably revert your commit and simply ask people to configure PKG_CONFIG_PATH appropriately in a post message