To atone for 1d7f9d5b4a59b3e, the revert of 4224b3f73110f6f.
At least it's fast again, even if it's shelling out to cmd.exe (once now).
Updates #1478
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This reverts commit 4224b3f73110f6f0c6268eb1ae943bc24cf89baf.
From https://github.com/tailscale/tailscale/pull/1494#discussion_r594852889 ...
> Actually, I want all four numbers back. I spent the evening
> debugging an issue for a user running an old version of Windows
> and then going to to
> https://en.wikipedia.org/wiki/Windows_10_version_history_(version_1809)
> and reading all the revision notes in the footnotes of that wikipedia
> page.
>
> I'm going to revert this for now for Tailscale 1.6. We can land it
> again later when we figure out how to get the fourth numbers.
Updates #1478
