Add a python-wrapped opencv, complete with SIFT support

Change-Id: I06cd05a8974670fb886123ef24e4c44c2a985362
diff --git a/build_tests/BUILD b/build_tests/BUILD
index a4c5829..0e3b8f7 100644
--- a/build_tests/BUILD
+++ b/build_tests/BUILD
@@ -115,3 +115,12 @@
     srcs = ["python_fbs.py"],
     deps = [":test_python_fbs"],
 )
+
+py_test(
+    name = "python3_opencv",
+    srcs = ["python_opencv.py"],
+    default_python_version = "PY3",
+    main = "python_opencv.py",
+    srcs_version = "PY2AND3",
+    deps = ["@opencv_contrib_nonfree_amd64//:python_opencv"],
+)
diff --git a/build_tests/python_opencv.py b/build_tests/python_opencv.py
new file mode 100644
index 0000000..c353c79
--- /dev/null
+++ b/build_tests/python_opencv.py
@@ -0,0 +1,6 @@
+#!/usr/bin/python3
+
+import cv2
+
+if __name__ == '__main__':
+  cv2.xfeatures2d.SIFT_create()