only the tests can't cope with the libs in the path

appveyor.yml

@@ -16,7 +16,7 @@ install:
     - curl -sSf -o rustup-init.exe https://win.rustup.rs/
     - rustup-init.exe -y --default-host %TARGET% --default-toolchain nightly
     - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
-    - cp C:\Users\appveyor\.rustup\toolchains\nightly-%TARGET%\bin\*.dll .
+    - copy C:\Users\appveyor\.rustup\toolchains\nightly-%TARGET%\bin\*.dll .
     - if defined MSYS2_BITS set PATH=%PATH%;C:\msys64\mingw%MSYS2_BITS%\bin
     - rustc -V
     - cargo -V
@@ -28,6 +28,7 @@ test_script:
     - cargo build --features debugging
     - cargo test --features debugging
     - copy clippy_tests\target\debug\cargo-clippy.exe C:\Users\appveyor\.cargo\bin\
+    - set PATH=%PATH%;C:\Users\appveyor\.rustup\toolchains\nightly-%TARGET%\bin
     - cargo clippy -- -D clippy
     - cd clippy_lints && cargo clippy -- -D clippy && cd ..