Obey tramp-histfile-override in remote direct async processes

* doc/emacs/custom.texi (Connection Variables):
Mention `permanent-local' symbol property.

* lisp/net/tramp-sh.el (tramp-histfile-override):
Add ;;;###tramp-autoload cookie and `permanent-local' symbol
property.

* lisp/net/tramp.el (tramp-handle-make-process):
Obey `tramp-histfile-override'.  (Bug#71049)

1 files changed, 7 insertions, 0 deletions

diff --git a/doc/emacs/custom.texi b/doc/emacs/custom.texi
index 4725af0ee5f..0d695032d77 100644
--- a/doc/emacs/custom.texi
+++ b/doc/emacs/custom.texi
@@ -1607,6 +1607,13 @@ matches all buffers with a remote default directory.
 and setting these profiles to criteria which could match in parallel.
 It is unspecified which variable value is used then.
 
+  Be also careful when setting connection-local variables in a buffer,
+which changes its major mode afterwards.  Because all buffer-local
+variables will be killed when changing the major mode, the
+connection-local variable's value would be lost.  You can prevent this
+by setting the respective variable's @code{permanent-local} symbol
+property to non-@code{nil}.
+
 @node Key Bindings
 @section Customizing Key Bindings
 @cindex key bindings