Merge pull request #1212 from caisq/r0.7-dev2.

util/python/python_config.sh

@@ -80,9 +80,9 @@ function setup_python {
     fi
   done
 
-  ln -s "${python_include}" util/python/python_include
-  ln -s "${python_lib}" util/python/python_lib
-  ln -s "${numpy_include}" third_party/py/numpy/numpy_include
+  ln -sf "${python_include}" util/python/python_include
+  ln -sf "${python_lib}" util/python/python_lib
+  ln -sf "${numpy_include}" third_party/py/numpy/numpy_include
 
   # Write tools/bazel.rc
   echo "# Autogenerated by configure: DO NOT EDIT" > tools/bazel.rc