bug#34350: 27.0.50; ediff-revision broken with SVN backend + non ascii chars both in directory and in filename

[Eli Zaretskii]

> From: Vincent Belaïche <vincent.belaiche@gmail.com>
> Cc: Vincent Belaïche <vincent.belaiche@gmail.com> 
> Date: Thu, 07 Feb 2019 23:27:28 +0100
> 
> > Is this part relevant?  You didn't really think we refuse to support
> > non-ASCII file names, did you?
> 
> [...]
> 
> No, I did not, that was just a joke, sorry for not being funny.

Oh, that was a joke?  Sorry for not catching it.

> Concerning your patch, it made it work.

Thanks, pushed to the emacs-26 branch.

This only fixes some VC backends, there are others which bind
coding-system-for-write in their backend implementations, which looks
simply wrong to me.  I hope we will be able to fix those as well, but
perhaps not in Emacs 26.2, if the changes I have in mind will be
deemed unsafe.