Optional third argument PRESERVE-MODES non-nil means don't alter
the files modes. Normally we reinitialize them using `normal-mode'.
+This function binds `revert-buffer-in-progress-p' non-nil while it operates.
+
If the value of `revert-buffer-function' is non-nil, it is called to
do all the work for this command. Otherwise, the hooks
`before-revert-hook' and `after-revert-hook' are run at the beginning