* lisp/net/tramp-archive.el (tramp-archive-handle-file-readable-p):
Use tramp-gvfs.
* lisp/net/tramp-gvfs.el (tramp-gvfs-handle-file-executable-p):
Check that FILENAME exists.
(tramp-gvfs-handle-file-readable-p): Check that FILENAME exists.
Use heuristic in case it cannot be determined correctly.