temporary fix for pip api changes

Author: skvark

setup.py

@@ -26,7 +26,7 @@ def main():
     if os.path.exists('.git'):
 
         import pip.vcs.git
-        g = pip.vcs.git.Git()
+        g = pip._internal.vcs.git.Git() # NOTE: pip API's are internal, this has to be refactored
 
         g.run_command(["submodule", "sync"])
         g.run_command(["submodule", "update", "--init", "--recursive", cmake_source_dir])