(comint-dynamic-complete-as-filename): Save end of match before calling other

functions.  Handle non-match too.

lisp/comint.el

@@ -1836,11 +1836,14 @@ See `comint-dynamic-complete-filename'.  Returns t if successful."
   (let* ((completion-ignore-case nil)
 	 (completion-ignored-extensions comint-completion-fignore)
 	 (success t)
-	 (filename (or (comint-match-partial-filename) ""))
-         (pathdir (file-name-directory filename))
-         (pathnondir (file-name-nondirectory filename))
-         (directory (if pathdir (comint-directory pathdir) default-directory))
-	 (completion (file-name-completion pathnondir directory)))
+	 (filename (comint-match-partial-filename))
+	 endpos pathdir pathnondir directory completion)
+    (setq endpos (if filename (match-end 0) (point)))
+    (or filename (setq filename ""))
+    (setq pathdir (file-name-directory filename)
+	  pathnondir (file-name-nondirectory filename)
+	  directory (if pathdir (comint-directory pathdir) default-directory)
+	  completion (file-name-completion pathnondir directory))
     (cond ((null completion)
            (message "No completions of %s" filename)
 	   (setq success nil))
@@ -1851,7 +1854,7 @@ See `comint-dynamic-complete-filename'.  Returns t if successful."
            (comint-dynamic-list-filename-completions))
           (t                            ; Completion string returned.
            (let ((file (concat (file-name-as-directory directory) completion)))
-             (goto-char (match-end 0))
+             (goto-char endpos)
              (insert (substring (directory-file-name completion)
                                 (length pathnondir)))
              (cond ((symbolp (file-name-completion completion directory))