Incorrect UTF-8 invalid code point replacement handling

[ktakashi]

Not sure if I should report here but seems this is the only active repository for Mosh.

The following script, I believe, should print #\g twice but #<eof-object> twice.

(import (rnrs))

(define buf-size 10)
(define bv (make-bytevector buf-size (char->integer #\a)))
(define (bytevector-append . bvs)
  (let* ((len (fold-left (lambda (sum bv) 
                           (+ (bytevector-length bv) sum)) 0 bvs))
         (r (make-bytevector len)))
    (fold-left (lambda (off bv)
                 (let ((len (bytevector-length bv)))
                   (bytevector-copy! bv 0 r off len)
                   (+ off len)))
               0 bvs)
    r))

(let ((bv2 (bytevector-append bv #vu8(#xe0 #x67 #x0a))))
  (call-with-port (transcoded-port 
                   (open-bytevector-input-port bv2) 
                   (make-transcoder (utf-8-codec)
                                    (eol-style lf)
                                    (error-handling-mode replace)))
    (lambda (in)
      (get-string-n in (+ 1 buf-size)) ;; read until invalid code point
      (write (get-char in)) (newline)))
  (call-with-port (transcoded-port 
                   (open-bytevector-input-port #vu8(#xe0 #x67 #x0a))
                   (make-transcoder (utf-8-codec)
                                    (eol-style lf)
                                    (error-handling-mode replace)))
    (lambda (in)
      (get-char in)
      (write (get-char in)) (newline))))
(flush-output-port (current-output-port))

Version:
Mosh R6RS scheme interpreter, version 0.2.7 (mosh-0.2.7-937-g6ba77b8 Tue, 23 Sep 2014 02:52:15 +0900)