bug#37527: [PATCH] Install C source code for for debugging help

[Eli Zaretskii <eliz@gnu.org>]

> Cc: stefan@marxist.se, michael.albinus@gmx.de, rgm@gnu.org,
>  37527@debbugs.gnu.org
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Thu, 23 Jan 2020 09:42:10 -0800
> 
> On 1/23/20 6:23 AM, Eli Zaretskii wrote:
> > if Emacs was installed with the
> > sources, but the original source tree where it was built still exists,
> > where will source-directory point after your changes?
> 
> It'll point to the original source tree if you're running Emacs out of 
> the build directory. If you're running Emacs out of the installed 
> directory, it will point to the installed source tree.

In that case, I will repeat my suggestion to have a separate variable
for the installed sources, because otherwise we are making an
incompatible behavior change.

> > Let's consider builds
> > that aren't meant to be reproducible.
> 
> Although we can do that, generally speaking it's better when there's no 
> difference between reproducible and irreproducible builds, as that's one 
> less thing to worry about when maintaining and debugging.

All the rest being equal, yes.  But all the rest is not equal in this
case, because your proposal changes a long-standing behavior in a very
reasonable use case.