powershell -> cmd.exe

appveyor.yml

@@ -8,10 +8,7 @@ install:
   - curl -sSf -o rustup-init.exe https://win.rustup.rs
   - rustup-init.exe --default-host x86_64-pc-windows-msvc --default-toolchain nightly -y
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-  - ps: >-
-      If ($Env:TARGET -eq 'i686-pc-windows-msvc') {
-        rustup target add $Env:TARGET
-      }
+  - if "%TARGET%"=="i686-pc-windows-msvc" ( rustup target add %TARGET% )
   - rustc -Vv
   - cargo -V