* tramp.texi (Remote processes): Let-bind environment variables to

`process-environment' when running `process-file' or `start-file-process'.

doc/misc/ChangeLog

+2014-11-23  Michael Albinus  <michael.albinus@gmx.de>
+
+	* tramp.texi (Remote processes): Let-bind environment variables to
+	`process-environment' when running `process-file' or
+	`start-file-process'.
+
 2014-11-19  Ivan Shmakov  <ivan@siamics.net>
 
 	* eww.texi (Basics): Document `eww-history-limit'.

doc/misc/tramp.texi

@@ -2711,6 +2711,21 @@ following code in your @file{.emacs}:
   (setq tramp-remote-process-environment process-environment))
 @end lisp
 
+When running @code{process-file} or @code{start-file-process} on a
+remote @code{default-directory}, the default settings in
+@code{process-environment} are not used as it is the case for local
+processes.  However, if you need environment variables other than set
+in @code{tramp-remote-process-environment}, you can let-bind them to
+@code{process-environment}. Only those variables will be set then:
+
+@lisp
+(let ((process-environment (cons "HGPLAIN=1" process-environment)))
+  (process-file @dots{}))
+@end lisp
+
+This works only for environment variables which are not set already in
+@code{process-environment}.
+
 If you use other @value{emacsname} packages which do not run
 out-of-the-box on a remote host, please let us know.  We will try to
 integrate them as well.  @xref{Bug Reports}.