debug clock skew

tools/internal_ci/helper_scripts/prepare_build_macos_rc

@@ -59,4 +59,7 @@ export PYTHONPATH=/Library/Python/3.4/site-packages
 # set xcode version for Obj-C tests
 sudo xcode-select -switch /Applications/Xcode_8.2.1.app/Contents/Developer
 
+# TODO(jtattermusch): better debugging of clock skew, remove once not needed
+date
+
 git submodule update --init

tools/internal_ci/macos/grpc_run_tests_matrix.sh

@@ -28,6 +28,9 @@ ps aux | grep port_server\\.py | awk '{print $2}' | xargs kill -9
 # Reveal leftover processes that might be left behind by the build
 ps aux | grep -i kbuilder
 
+# TODO(jtattermusch): better debugging of clock skew, remove once not needed
+date
+
 echo 'Exiting gRPC main test script.'
 
 if [ "$FAILED" != "" ]