Re: Patch: new function process-file (call-process with file handlers)

[Luc Teirlinck]

This apparently breaks `C-x v =' and other vc commands.

The INFILE argument to process-file is optional and hence, can be nil.
But process-file unconditionally does (file-local-copy infile).  If
infile is nil that leads to:

wrong-type-argument stringp nil

That is indeed the error generated by `C-x v ='.

Sincerely,

Luc.