Currently, the .opam-switch/environment file is wrongly parsed by opam when the value of a variable is empty:

If my file is

CPP     =               Updated\ by\ package\ ocaml-base-compiler

CPP will wrongly be set to Updated by package ocaml-base-compiler. This will prevent creating another switch after eval $(opam env) because ocaml will fail to compile with a wrong CPP var.

An immediate fix should be to stop writing these "Updated by package $name" comments. A long-term fix should be to use a more standard format.