A smidge more information at:
https://forums.gentoo.org/viewtopic-p-8058954.html?sid=5e043f49e6dc6fdf007a11fc2fa4fad5

I wish I had time to debug the issue, but unfortunately I do not.  I'm
taking the "Could be a good time to get paranoid" advice... wiping,
rebuilding, and moving on.

D. Paddy

On Tue, May 2, 2017 at 11:56 AM, Glenn Morris <rgm@gnu.org> wrote:

> d paddy wrote:
>
> > If the cable to the router is disconnected then emacs hangs.
>
> I can't reproduce this. If I start Emacs, then turn off my internet
> connection, Emacs continues to work fine.
>
> > This is a bug because emacs should not be spying on people (phoneing
> > home).
>
> I can assure you Emacs doesn't phone home. We don't care what you and
> Emacs get up to. :)
>
> You can of course install add-ons that do anything. And you can use
> Emacs to access remote files and servers. Any of these things could
> cause a hang if your connection drop. Otherwise the only issue in this
> area I know of is the startup hang due to domain name issues, documented
> in PROBLEMS.
>
> Unless you can provide a reproducible recipe starting from emacs -Q,
> this report is unlikely to lead anywhere. You could also try attaching a
> debugger to Emacs to see what it is waiting for.
>