Hi again,

I decided to just implement the fix and see what people think of it.  Simply removing a check for non-interactive invocation solves the issue and now 'guix shell' and 'guix shell -- make' act exactly the same except for which command they run.  Patch attached.

The interactive check is a feature, not a bug:

https://issues.guix.gnu.org/50960#69:
[...]

Agreed. The automatic reading of guix.scm/manifest.scm, if we keep it,

should only happen in interactive use; I’ll double-check and make sure

this is the case.

Greetings,
Maxime.