visited-file-modtime not updated for tramp files on local host

[Gilles Pion]

I have a problem with last tramp version (2.1.16) when editing files whose
"tramp-local-host-p" predicate is true (like "/<user>@localhost:/<pathname")


It seems that, in this situation, "visited-file-modtime" is not updated 
and this leads to messages like this one:
"<file> has changed since visited or saved.  Save anyway? (y or n) "

I suspect a problem around the shortcut taken inside tramp-handle-write-region
around the comment 
"Short track: if we are on the local host, we can run directly."

--
Gilles