trivial-build-system and which

[Stephen Scheck]

This package definition always fails with #f returned by `(which "bash")`
... am I missing something?

    (build-system trivial-build-system)
    (arguments
      `(#:builder
         (begin
           (use-modules (guix build utils))
           (invoke "make" (string-append "SHELL=" (which "bash")) "..."))))
    (native-inputs
      `(("bash" ,bash)
        ("make" ,gnu-make)