bug#27435: patch for dired-mouse-find-file-other-window

[Eli Zaretskii]

> Date: Sun, 27 Aug 2017 18:02:43 +0900 (JST)
> Cc: 27435@debbugs.gnu.org, tkk@misasa.okayama-u.ac.jp
> From: Tak Kunihiro <tkk@misasa.okayama-u.ac.jp>
> 
> > But you could have the same effect by rebinding mouse-2 to another
> > function.  We just need to add such a function, which should work like
> > dired-mouse-find-file-other-window, but visit the file in the same
> > window.  That sounds like a better alternative for this use case,
> > because customizing a function-valued variable is trickier for users
> > than rebinding keys.
> 
> I agree.
> 
> Then the new function `dired-mouse-find-file-this-window' will look
> very similar to `dired-mouse-find-file-other-window' but two lines.
> Is that OK?

We could factor out the common part into a new function, and then make
those two functions call it.