+;;; ...and a missing wrinkle in the original patch, dealing with
+;;; PEEK-CHAR/UNREAD-CHAR on ECHO-STREAMs, fixed by MRD patch
+;;; sbcl-devel 2002-11-18, merged ca. sbcl-0.7.9.66
+(assert (string=
+ (let* ((in-stream (make-string-input-stream "abc"))
+ (out-stream (make-string-output-stream))
+ (echo-stream (make-echo-stream in-stream out-stream)))
+ (unread-char (read-char echo-stream) echo-stream)
+ (peek-char #\a echo-stream)
+ (get-output-stream-string out-stream))
+ ;; (Before the fix, the LET* expression just signalled an error.)
+ "a"))