Different behavior when compiled with raco make

[tov]

Compiling with raco make makes it impossible to implement an interface in a different source file than where the interface is defined. In particular, objects of a class C that implements an interface I imported from another source file are not actually considered to implement interface I by the I? and I! contracts.

How to reproduce

1. Create a file lib.rkt containing:

   #lang dssl2
   
   interface I: pass

2. Create a file client.rkt containing:

   #lang dssl2
   
   import 'lib.rkt'
   
   class C (I):
       def __init__(self): pass
   
   # This should succeed because C implements I, but it fails if you run
   # `raco make` first. (It also fails in DrRacket.)
   let o: I! = C()

3. Run client.rkt:

   $ racket client.rkt
   $

4. Compile client.rkt and run it again:

   $ raco make client.rkt
   $ racket client.rkt
   o: broke its own contract;
    class C does not implement interface I
     in: I!
     contract from: (definition o)
     blaming: (definition o)
      (assuming the contract is correct)
     at: /Users/tov/Desktop/raco-make-weirdness/client.rkt:10.4
     context...:
      /Applications/Racket v7.4/collects/racket/contract/private/blame.rkt:347:0: raise-blame-error16
      "/Users/tov/Desktop/raco-make-weirdness/client.rkt": [running body]
      temp37_0
      for-loop
      run-module-instance!125
      perform-require!78
   $

5. Delete the compilation artifacts and run it again:

   $ rm -R compiled
   $ racket client.rkt
   $