Fix appveyor try 3

appveyor.yml

 environment:
-  # When this was added there were revocation check failures when using the
-  # libcurl backend as libcurl checks by default, but rustup doesn't provide the
-  # switch to turn this off. Switch to Reqwest which looks to not check for
-  # revocation by default like libcurl does.
-  RUSTUP_USE_REQWEST: 1
-  CARGO_HTTP_CHECK_REVOKE: false
   matrix:
   - TARGET: x86_64-pc-windows-gnu
-    MSYS2_BITS: 64
+    MSYS_BITS: 64
+    ARCH: x86_64
   - TARGET: i686-pc-windows-gnu
-    MSYS2_BITS: 32
+    MSYS_BITS: 32
+    ARCH: i686
   - TARGET: x86_64-pc-windows-msvc
   - TARGET: i686-pc-windows-msvc
 install:
-  - appveyor-retry appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
-  - rustup-init.exe -y --default-host %TARGET%
-  - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-  - if defined MSYS2_BITS set PATH=%PATH%;C:\msys64\mingw%MSYS2_BITS%\bin
-  - if defined MSYS2_BITS for %%I in (crt2.o dllcrt2.o libmsvcrt.a) do xcopy /Y "C:\msys64\mingw%MSYS2_BITS%\%ARCH%-w64-mingw32\lib\%%I" "C:\Program Files (x86)\Rust\lib\rustlib\%TARGET%\lib"
+  - if defined MSYS_BITS set PATH=C:\msys64\mingw%MSYS_BITS%\bin;C:\msys64\usr\bin;%PATH%;
+  - ps: Start-FileDownload "https://static.rust-lang.org/dist/rust-nightly-${env:TARGET}.exe"
+  - rust-nightly-%TARGET%.exe /VERYSILENT /NORESTART /DIR="C:\Program Files (x86)\Rust"
+  - set PATH=%PATH%;C:\Program Files (x86)\Rust\bin
+  - if defined MSYS_BITS for %%I in (crt2.o dllcrt2.o libmsvcrt.a) do xcopy /Y "C:\msys64\mingw%MSYS_BITS%\%ARCH%-w64-mingw32\lib\%%I" "C:\Program Files (x86)\Rust\lib\rustlib\%TARGET%\lib"
   - rustc -V
   - cargo -V