Rustup is unable to download on appveyor

[Marwes]

I originally encountered this issue on gluon's appveyor setup but it appears that rustup's own appveyor setup has the same problem. This may just be an issue on appveyor but since rustup's setup is also affected I figured opening an issue here was relevant.

Might be related to rust-lang/rust#43333 but the solution in that PR does not help.

Build started
git clone -q https://github.com/gluon-lang/gluon.git C:\projects\gluon
git fetch -q origin +refs/pull/279/merge:
git checkout -qf FETCH_HEAD
Running Install scripts
curl -sSf -o rustup-init.exe https://win.rustup.rs
rustup-init.exe --default-host %TARGET% --default-toolchain %CHANNEL% -y
info: syncing channel updates for 'stable-x86_64-pc-windows-msvc'
error: could not download file from 'https://static.rust-lang.org/dist/channel-rust-stable.toml.sha256' to 'C:\Users\appveyor\.rustup\tmp\ip9r_xhlefdoj47g_file'
info: caused by: error during download
info: caused by: [35] SSL connect error (schannel: next InitializeSecurityContext failed: Unknown error (0x80092013) - The revocation function was unable to check revocation because the revocation server was offline.)
Command exited with code 1

[Boddlnagg]

See https://users.rust-lang.org/t/appveyor-builds-failing-today/11949/3 and http://help.appveyor.com/discussions/problems/7115-curl-cant-download-files-through-ssl#comment_43044339. It's a problem on AppVeyor's side which should be fixed very soon.