Install the test deps in before_test

appveyor.yml

@@ -25,10 +25,13 @@ environment:
 install:
   # We need wheel installed to build wheels
   - "%PYTHON%\\python.exe -m pip install wheel"
-  - "%PYTHON%\\python.exe -m pip install -r requirements.txt -r test-requirements.txt"
+  - "%PYTHON%\\python.exe -m pip install -r requirements.txt"
 
 build: off
 
+before_test:
+  - "%PYTHON%\\python.exe -m pip install -r test-requirements.txt"
+
 test_script:
   # Put your test command here.
   # If you don't need to build C extensions on 64-bit Python 3.3 or 3.4,