Try to clone include submodules

appveyor.yml

@@ -10,6 +10,13 @@ environment:
       PYTHON_VERSION: "2.7.x" # currently 2.7.9
       PYTHON_ARCH: "64"
 
+clone_script:
+- cmd: >-
+    git clone -q --branch=%APPVEYOR_REPO_BRANCH% https://github.com/%APPVEYOR_REPO_NAME%.git %APPVEYOR_BUILD_FOLDER%
+    cd %APPVEYOR_BUILD_FOLDER%
+    git checkout -qf %APPVEYOR_REPO_COMMIT%
+    git submodule update --init --recursive
+
 install:
   # If there is a newer build queued for the same PR, cancel this one.
   # The AppVeyor 'rollout builds' option is supposed to serve the same