Network failure after using socks5 proxy on rustup 1.17.0

[KaneGreen]

Problem
Failed to make network request when update using socks5 proxy on 1.17.0.

Steps

0. The last time I updated my rustup is when stable-1.33.0 release, I can't remember which version that is.
1. Today, I run set https_proxy=socks5://127.0.0.1:1080 and rustup self update. The rustup upgraded to 1.17.0 successfully.
2. The I run rustup update nightly, and there cames an error.

info: syncing channel updates for 'nightly-x86_64-pc-windows-msvc'
error: could not download file from 'https://static.rust-lang.org/dist/channel-rust-nightly.toml.sha256' to 'C:\Users\myname\.rustup\tmp\kf4wksnp1qdcizk__file'
info: caused by: failed to make network request
info: caused by: https://static.rust-lang.org/dist/channel-rust-nightly.toml.sha256: an error occurred trying to connect: unexpected eof while tunneling
info: caused by: unexpected eof while tunneling

and my proxy soft only shows this:invalid socks handshake message.
3. Finally I run set https_proxy=http://127.0.0.1:1081 and rustup update nightly, it work well.

Possible Solution(s)
Use HTTP proxy.

Notes
OS: Windows 10 64bit 17763.79
Output of rustup --version:

rustup 1.17.0 (069c88ed6 2019-03-05)

Output of rustup show:

Default host: x86_64-pc-windows-msvc

installed toolchains
--------------------

stable-x86_64-pc-windows-gnu
stable-x86_64-pc-windows-msvc (default)
nightly-x86_64-pc-windows-msvc

active toolchain
----------------

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

[kinnison]

@seanmonstar Any chance reqwest will support socks proxying?

[seanmonstar]

There was a PR to add support in reqwest, it stalled due to the socks lib being blocking IO only (and reqwest tries to use non-blocking internally), but I can push it through anyways.

[seanmonstar]

reqwest v0.9.14 now has an optional socks cargo feature. By enabling it, I believe the combination with env_proxy should be enough to use SOCKS5 automatically.