Revert "Merge pull request #19581 from lidizheng/rf-signal"

This reverts commit 6d62eb1b70, reversing
changes made to 70dd0b9b3b.

src/python/grpcio_tests/tests/unit/_signal_handling_test.py

@@ -13,6 +13,8 @@
 # limitations under the License.
 """Test of responsiveness to signals."""
 
+from __future__ import print_function
+
 import logging
 import os
 import signal