[plt-scheme] compile: access from an uncertified context to unexported variable

Hello,

It appears that there's an incompatibility between the "extra.ss" module
and the "errortrace.ss" module.

This little snippet

  (require (lib "errortrace.ss" "errortrace"))
  (require (lib "extra.ss" "swindle"))
  (amb 3 4)

yields this message:

  Welcome to DrScheme, version 299.107-svn29jun2005.
  Language: Pretty Big (includes MrEd and Advanced).
  compile: access from an uncertified context to unexported variable
  from module: |,/usr/local/full-299.107/collects/swindle/extra|
  in: amb-fail

Any ideas?

++ Ken Williams