* mu4e: when moving messages, always reset the N flag

(since N (new) messages cannot have any other flags, you would loose
  e.g. the T flag when moving to trash; now, we remove the N flag, and the T
  flag remains)

emacs/mu4e-mark.el

@@ -249,16 +249,18 @@ If NO-CONFIRMATION is non-nil, don't ask user for confirmation."
 	(maphash
 	  (lambda (docid val)
 	    (let ((mark (car val)) (target (cdr val)))
+	      ;; note: whenever you do something with the message,
+	      ;; it looses its N (new) flag
 	      (case mark
-		(move   (mu4e~proc-move docid target))
+		(move   (mu4e~proc-move docid target "-N"))
 		(read   (mu4e~proc-move docid nil "+S-u-N"))
-		(unread (mu4e~proc-move docid nil "-S+u"))
+		(unread (mu4e~proc-move docid nil "-S+u-N"))
 		(flag   (mu4e~proc-move docid nil "+F-u-N"))
-		(unflag (mu4e~proc-move docid nil "-F"))
+		(unflag (mu4e~proc-move docid nil "-F-N"))
 		(trash
 		  (unless mu4e-trash-folder
 		    (error "`mu4e-trash-folder' not set"))
-		  (mu4e~proc-move docid mu4e-trash-folder "+T"))
+		  (mu4e~proc-move docid mu4e-trash-folder "+T-N"))
 		(delete (mu4e~proc-remove docid))
 		(otherwise (error "Unrecognized mark %S" mark)))))
 	  mu4e~mark-map))
@@ -308,4 +310,3 @@ action', return nil means 'don't do anything'"
 
 (provide 'mu4e-mark)
 ;; End of mu4e-mark.el
-

lib/mu-maildir.c

@@ -707,7 +707,8 @@ mu_maildir_get_flags_from_path (const char *path)
  * /home/user/Maildir/foo/bar/new/abc  and flags == MU_FLAG_REPLIED
  *    => /home/user/Maildir/foo/bar/cur
  *
- * so only difference is whether MuFlags matches MU_FLAG_NEW is set or not
+ * so the difference is whether MuFlags matches MU_FLAG_NEW is set or
+ * not; and in the latter case, no other flags are allowed.
  *
  */
 static gchar*