[racket-dev] Fix to module reader?

I'm running into an internal error with the syntax/module-reader
library with the given test program, and wanted to double check with
someone else before committing the fix upstream.


The test file is:

    https://gist.github.com/dyoo/5272982


When I run this under an unpatched module reader, I see the following error:

128-110-73-138:Desktop dyoo$ raco test prepend-lang-line.rkt
testing prepend-lang-line.rkt
-: contract violation
  expected: number?
  given: #f
  argument position: 2nd
  other arguments...:
   16
  context...:
   /Applications/Racket
v5.3.2/collects/syntax/module-reader.rkt:173:2: wrap-internal
   wrap-internal/wrapper
   /Users/dyoo/Desktop/prepend-lang-line.rkt: [running body]
   /Applications/Racket v5.3.2/collects/compiler/commands/test.rkt:
[running body]
   /Applications/Racket v5.3.2/collects/raco/raco.rkt: [running body]
   /Applications/Racket v5.3.2/collects/raco/main.rkt: [running body]




My proposed patch is:


https://github.com/dyoo/racket/commit/9322570e3e0210b99ec8a85dca52b62b4dde66fd




Does this look ok?  Also, if I do push this upstream, how do I attach
my test file so it gets run as part of the DrDr regression suite?