Integrated Terminal glitched output with docker push

[hassanselim0]

• VSCode Version: 1.21.1
• OS Version: Windows 10 Pro Version 1709

Steps to Reproduce:

1. Run docker push on the integrated terminal while it's small (enough to not show all the layers)
2. Attempt to scroll while the layers are being uploaded
3. Notice that lines (with layer progress change) get duplicated

Screenshot: (notice how the c041efd84434 line is duplicated)

I don't believe that this is related to #36630 because I don't get that io error and the push completes successfully, but the progress bars glitch in this way.
This issue might apply to other CLI tools that modify previous lines in the console, not just docker push, but I haven't encountered any of these myself so I can't confirm.

Note: I'm using cmd in the integrated terminal, I haven't tested with Powershell.

Does this issue occur when all extensions are disabled?: Probably

[Tyriar]

This is one of the issues caused by winpty, tracking in #45693

[hassanselim0]

@Tyriar I'm not sure which of the linked issues in that meta-issue is the duplicate.
My line duplication issue doesn't happen when resizing, it happens when scrolling then a line gets updated (like the progress bar).

[Tyriar]

@hassanselim0 I edited the issue to call this one out explicitly.