string-downcase in scheme-with-scsh

["Mike Simpson" <mike.simpson@doit.wisc.edu>]

Forgive me if there's an obvious answer to this, but I didn't see
it in the SCSH FAQ.

When using scsh in interactive mode, the (string-downcase) function
performs as expected:

  Welcome to scsh 0.6.4 (Olin Shivers)
  Type ,? for help.
  > (string-downcase "FooBarBat")
  "foobarbat"

However, when I bury a call to (string-downcase) inside a structure
definition, even when I use (open scheme-with-scsh), scsh throws
the following error:

  Warning: undefined variables
           #{Package 227 test}
           string-downcase

  Error: undefined variable
         string-downcase
         (package test)

If I add the "srfi-13" module to the (open) call, i.e.

  (open scheme-with-scsh srfi-13)

then everything works fine.

Is this expected behavior, or a bug in the interface exports of
the scheme-with-scsh structure?

Thanks,

-mgs