bug#41640: 28.0.50; shell startup very slow when init file is used

[Lars Ingebrigtsen]

Pip Cet <pipcet@gmail.com> writes:

> There's also an alternative explanation, which is that the systems
> available back then might have discarded input arriving before the
> prompt was first written. But, if that's the case today, it's likely to
> be done for a reason, and we shouldn't try to prevent it.

The person reporting the bug says that Pip's patch fixes the problem.
There was some discussion about what the original code from the 90s was
trying to fix, and the answer was...  that we don't know.

So I just went ahead and applied the patch.  I tried it here, and it
didn't break anything, but there are many systems out there.  But I
think it's worth a try, so I'm pushing it to Emacs 28.  If it breaks
anything, we should revert it.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no