"Protected" error when re-providing a third party function

Hello,
I attempted to re-provide a function from a third party module (call from mischief/function) in my module, without modification. E.g.:

(require (only-in mischief/function call))
(provide call)

The code built successfully and the tests passed, but the Scribble docs failed to build with dynamic-require: name is protected (full error pasted below).

As a workaround, I manually copied the implementation from the third party source and provided it afresh from within my module without require-ing it; this is the commit that does that. This works, as expected. [Note: I just noticed that there is a redundant deftogether in that commit - this does not affect the error either way (I just checked).]

Environment
Racket 7.8 CS

Full error message:

Note that the error implicates a module (composition.scrbl) that isn't modified by the offending code.

examples: exception raised in example
  error: "dynamic-require: name is protected\n  name: 'syntax-local-expand-observer\n  module: #<resolved-module-path:'#%expobs>"
  context...:
   do-error
   .../scribble/eval.rkt:308:23: with-handlers-handler102
   .../private/more-scheme.rkt:163:2: select-handler/no-breaks
   .../scribble/eval.rkt:356:9
   .../private/map.rkt:40:19: loop
   [repeats 6 more times]
   .../private/manual-vars.rkt:218:40
   .../private/manual-vars.rkt:167:0: *deftogether
   interpret
   loop
   interpret
   [repeats 3 more times]
   proc
   call-in-empty-metacontinuation-frame
   body of "/Users/siddhartha/work/lisp/racket/relation/scribblings/composition.scrbl"
   interpret-expr

  context...:
   do-error
   call-in-empty-metacontinuation-frame
   .../setup/parallel-do.rkt:332:4: !work-done method in list-queue%
   .../setup/parallel-do.rkt:282:17
   .../setup/parallel-do.rkt:236:4
   dynamic-wind
   .../setup/scribble.rkt:138:0: setup-scribblings
   call-in-empty-metacontinuation-frame
   winder-dummy
   .../setup/setup-core.rkt:72:0: setup-core
   call-in-empty-metacontinuation-frame
   body of "/Applications/Racket v7.8/collects/setup/main.rkt"
   temp35_0
   run-module-instance!
   call-in-empty-metacontinuation-frame
   body of "/Applications/Racket v7.8/collects/raco/main.rkt"

Reproduce the documentation build failure from the require/provide example involving mischief/function's call, then inspect scribblings/composition.scrbl and the Scribble evaluation path named in the stack trace, including scribble/eval.rkt. Done means the documentation build no longer raises dynamic-require: name is protected when the third-party function is re-provided.