23.0.60; unicode-2, rmail-convert-to-babyl-format loops infinitely

[dnz]

Debugger entered--Lisp error: (quit)
  rmail-decode-region(184 644 koi8-r)
  rmail-convert-to-babyl-format()
  rmail-convert-file()
  rmail-mode()
  call-interactively(rmail-mode t nil)
  execute-extended-command(nil)
  call-interactively(execute-extended-command nil nil)

You can use the mail below (can be decoded with base64-decode-region) as an 
example:

DAowLCB1bnNlZW4sLApSZXR1cm4tcGF0aDogPGRuekBiay5ydT4KUmVjZWl2ZWQ6IGZyb20gbWFp
bCBieSBmMTA1Lm1haWwucnUgd2l0aCBsb2NhbCAKCWlkIDFKRFBtcy0wMDBCd1QtMDAKCWZvciBk
bnpAYmsucnU7IEZyaSwgMTEgSmFuIDIwMDggMjI6NDM6MzAgKzAzMDAKRnJvbTogZG56IDxkbnpA
YmsucnU+ClRvOiBkbnpAYmsucnUKU3ViamVjdDogdGVzdApNaW1lLVZlcnNpb246IDEuMApEYXRl
OiBGcmksIDExIEphbiAyMDA4IDIyOjQzOjMwICswMzAwClJlcGx5LVRvOiBkbnogPGRuekBiay5y
dT4KQ29udGVudC1UeXBlOiB0ZXh0L3BsYWluOyBjaGFyc2V0PWtvaTgtcgpDb250ZW50LVRyYW5z
ZmVyLUVuY29kaW5nOiA4Yml0Ck1lc3NhZ2UtSWQ6IDxFMUpEUG1zLTAwMEJ3VC0wMC5kbnotYmst
cnVAZjEwNS5tYWlsLnJ1PgoKdGVzdAoKHw==


PS: Curiously, with the change below it works:

--- rmail.el    2008-01-11 19:02:36.000000000 +0000
+++ rmail.el~   2008-01-11 20:14:00.000000000 +0000
@@ -1918,7 +1918,7 @@
 
 ;; the  rmail-break-forwarded-messages  feature is not implemented
 (defun rmail-convert-to-babyl-format ()
-  (let ((count 0) start
+  (let ((count 0) start xxx
        (case-fold-search nil)
        (buffer-undo-list t)
        (invalid-input-resync
@@ -2021,7 +2021,9 @@
                                            rmail-mime-charset-pattern
                                            start t))))
                                  (intern (downcase (match-string 1))))))
+                        (setq xxx (point))
                         (rmail-decode-region start (point) mime-charset)))))
+              (goto-char xxx)
               ;; Add an X-Coding-System: header if we don't have one.
               (save-excursion
                 (goto-char start)