Warning: Invalid argument
  In file `svnwiki-sxml.scm:709',
  In module `svnwiki-sxml',
  In procedure `svnwiki-signature->identifier',
  In a local procedure,
  In a local procedure,
  In a local procedure,
  In procedure `loop',
  In procedure call:

    (scheme#symbol->string id)

  Argument #1 to procedure `symbol->string' has an invalid type:

    keyword

  The expected type is:

    symbol

  This is the expression:

    id

  Procedure `symbol->string' from module `scheme' has this type:

    (symbol -> string)