[PATCH] interactive: make sure buffer is flushed before waiting for user input

[Matt Harbison]

On Sat, 05 Aug 2017 16:20:15 -0400, Kostia Balytskyi <ikostia at fb.com>  
wrote:

> # HG changeset patch
> # User Kostia Balytskyi <ikostia at fb.com>
> # Date 1501964349 25200
> #      Sat Aug 05 13:19:09 2017 -0700
> # Node ID 6065399003c83344df50209068ea85d82b3382d7
> # Parent  609606d217659e0a6c1cf6f907b6512be5340e57
> interactive: make sure buffer is flushed before waiting for user input

Needs '(issue5587)' and applied to stable?  I'm not sure if issue5604,  
which was marked as a duplicate, actually is.

> Without this patch on Windows 'hg ci -i' hangs waiting for user input
> and "examine changes to 'file'? [Ynesfdaq?]" is never displayed (at least
> if the diff is sufficiently small). When Ctrl+C is pressed, this prompt
> becomes visible, which suggests that the buffer just wasn't flushed.
> I've never seen this happening on Linux, but this looks harmless enought
> to not platform-gate it.