bug#28691: [PATCH] Add file name handler support for 'make-process' (Bug#28691)

[Eli Zaretskii <eliz@gnu.org>]

> From: Philipp Stephani <p.stephani2@gmail.com>
> Cc: 28691@debbugs.gnu.org,
> 	Philipp Stephani <phst@google.com>
> Date: Mon, 17 Dec 2018 21:47:46 +0100
> 
> * src/process.c (Fmake_process): Add new keyword argument
> ':file-handler'.
> (syms_of_process) <make-process, :file-handler>: Define new symbols.
> 
> * lisp/files.el (file-name-non-special): Add support for
> 'make-process'.
> 
> * test/src/process-tests.el (make-process/file-handler/found)
> (make-process/file-handler/not-found)
> (make-process/file-handler/disable): New unit tests.
> (process-tests--file-handler): New helper function.
> 
> * test/lisp/files-tests.el
> (files-tests-file-name-non-special-make-process): New unit test.
> 
> * doc/lispref/files.texi (Magic File Names): Document that
> 'make-process' can invoke file name handlers.
> 
> * doc/lispref/processes.texi (Asynchronous Processes): Document
> ':file-handlers' argument to 'make-process'.

Thanks, this LGTM, but some of the tests use the Emacs binary, while
others still use /bin/true for some reason.  What am I missing?

Please also include etc/NEWS change in the log message.