The third argument to `open()` in `-|` mode is passed to a shell if it's
a string. In my case the store URI contains
`?secret-key=${signingKey.directory}/secret&compression=zstd`
For the `nix store cat` case this means that
* until `&` the process will be started in the background. This fails
immediately because no path to cat is specified.
* `compression=zstd` is a variable assignment
* the `$path` argument to `store cat` is attempted to be executed as
another command
Passing just the list solves the problem.
Maximilian Bosch