Improve lock-pid handling in Tramp

* lisp/net/tramp-cache.el: Remove comment.

* lisp/net/tramp-gvfs.el (tramp-gvfs-maybe-open-connection):
* lisp/net/tramp-rclone.el (tramp-rclone-maybe-open-connection):
* lisp/net/tramp-sshfs.el (tramp-sshfs-maybe-open-connection):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-maybe-open-connection):
Do not set "lock-pid" connection-property.
(tramp-sudoedit-handle-delete-file): Use "rm -f".

* lisp/net/tramp.el (tramp-test-message): Extend for buffers w/o
remote default-directory.
(tramp-lock-pid): New defvar.
(tramp-get-lock-pid): Reimplement.

lisp/net/tramp-cache.el

@@ -49,8 +49,6 @@
 ;;   an open connection.  Examples: "scripts" keeps shell script
 ;;   definitions already sent to the remote shell, "last-cmd-time" is
 ;;   the time stamp a command has been sent to the remote process.
-;;   "lock-pid" is the timestamp a (network) process is created, it is
-;;   used instead of the pid in file locks.
 ;;
 ;; - The key is nil.  These are temporary properties related to the
 ;;   local machine.  Examples: "parse-passwd" and "parse-group" keep

lisp/net/tramp-gvfs.el

@@ -2125,9 +2125,6 @@ connection if a previous connection has died for some reason."
       (process-put p 'vector vec)
       (set-process-query-on-exit-flag p nil)
 
-      ;; Mark process for filelock.
-      (tramp-set-connection-property p "lock-pid" (truncate (time-to-seconds)))
-
       ;; Set connection-local variables.
       (tramp-set-connection-local-variables vec)))
 

lisp/net/tramp-rclone.el

@@ -368,10 +368,6 @@ connection if a previous connection has died for some reason."
 	  (process-put p 'vector vec)
 	  (set-process-query-on-exit-flag p nil)
 
-	  ;; Mark process for filelock.
-	  (tramp-set-connection-property
-	   p "lock-pid" (truncate (time-to-seconds)))
-
 	  ;; Set connection-local variables.
 	  (tramp-set-connection-local-variables vec)))
 

lisp/net/tramp-sshfs.el

@@ -345,9 +345,6 @@ connection if a previous connection has died for some reason."
       (process-put p 'vector vec)
       (set-process-query-on-exit-flag p nil)
 
-      ;; Mark process for filelock.
-      (tramp-set-connection-property p "lock-pid" (truncate (time-to-seconds)))
-
       ;; Set connection-local variables.
       (tramp-set-connection-local-variables vec)))
 

lisp/net/tramp-sudoedit.el

@@ -336,7 +336,7 @@ absolute file names."
     (if (and delete-by-moving-to-trash trash)
 	(move-file-to-trash filename)
       (unless (tramp-sudoedit-send-command
-	       v "rm" (tramp-compat-file-name-unquote localname))
+	       v "rm" "-f" (tramp-compat-file-name-unquote localname))
 	;; Propagate the error.
 	(with-current-buffer (tramp-get-connection-buffer v)
 	  (goto-char (point-min))
@@ -788,9 +788,6 @@ connection if a previous connection has died for some reason."
       (process-put p 'vector vec)
       (set-process-query-on-exit-flag p nil)
 
-      ;; Mark process for filelock.
-      (tramp-set-connection-property p "lock-pid" (truncate (time-to-seconds)))
-
       ;; Set connection-local variables.
       (tramp-set-connection-local-variables vec)
 

lisp/net/tramp.el

@@ -2233,10 +2233,14 @@ the resulting error message."
 
 (defun tramp-test-message (fmt-string &rest arguments)
   "Emit a Tramp message according `default-directory'."
-  (if (tramp-tramp-file-p default-directory)
-      (apply #'tramp-message
-	     (tramp-dissect-file-name default-directory) 0 fmt-string arguments)
-    (apply #'message fmt-string arguments)))
+  (cond
+   ((tramp-tramp-file-p default-directory)
+    (apply #'tramp-message
+	   (tramp-dissect-file-name default-directory) 0 fmt-string arguments))
+   ((tramp-file-name-p (car tramp-current-connection))
+    (apply #'tramp-message
+	   (car tramp-current-connection) 0 fmt-string arguments))
+   (t (apply #'message fmt-string arguments))))
 
 (put #'tramp-test-message 'tramp-suppress-trace t)
 
@@ -3958,16 +3962,19 @@ Return nil when there is no lockfile."
 	       (insert-file-contents-literally lockname)
 	       (buffer-string))))))
 
+(defvar tramp-lock-pid nil
+  "A random nunber local for every connection.
+Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'")
+
 (defun tramp-get-lock-pid (file)
   "Determine pid for lockfile of FILE."
-  ;; Some Tramp methods do not offer a connection process, but just a
-  ;; network process as a place holder.  Those processes use the
-  ;; "lock-pid" connection property as fake pid, in fact it is the
-  ;; time stamp the process is created.
-  (let ((p (tramp-get-process  (tramp-dissect-file-name file))))
-    (number-to-string
-     (or (process-id p)
-	 (tramp-get-connection-property p "lock-pid" (emacs-pid))))))
+  ;; Not all Tramp methods use an own process.  So we use a random
+  ;; number, which is as good as a process id.
+  (with-current-buffer
+      (tramp-get-connection-buffer (tramp-dissect-file-name file))
+    (or tramp-lock-pid
+	(setq-local
+	 tramp-lock-pid (number-to-string (random most-positive-fixnum))))))
 
 (defconst tramp-lock-file-info-regexp
   ;; USER@HOST.PID[:BOOT_TIME]