progress bar overly precise

[rbtcollins]

Problem

The progress bar during installation can be overly precise like so:
3.1 MiB / 10.4 MiB ( 30 %) 46.4 KiB/s ETA: 2.6780612989403734 min 40.68367793642241 s
I would expect instead to see something like:
3.1 MiB / 10.4 MiB ( 30 %) 46.4 KiB/s ETA: 2min 40s

Steps

1. Install nightly on Windows (See Optimize disk access during install #904 )

Possible Solution(s)

Notes

Output of rustup --version: rustup 1.17.0 (069c88ed6 2019-03-05)
Output of rustup show: ```
rustup show
Default host: x86_64-pc-windows-msvc

installed toolchains

stable-x86_64-pc-windows-msvc
nightly-x86_64-pc-windows-msvc

active toolchain

stable-x86_64-pc-windows-msvc (default)
rustc 1.33.0 (2aa4c46cf 2019-02-28)

[kinnison]

This is a duplicate of #1696 and #1731 and was fixed in #1699 - the fix will be in rustup 1.18.0