Fix C/C++ test filtering
diff --git a/tools/jenkins/run_c_cpp_test.sh b/tools/jenkins/run_c_cpp_test.sh
index a7e5745..afa2e78 100755
--- a/tools/jenkins/run_c_cpp_test.sh
+++ b/tools/jenkins/run_c_cpp_test.sh
@@ -35,10 +35,12 @@
# Enter the gRPC repo root
cd $(dirname $0)/../..
-AFFECTS_C_CPP=`python -c 'import sys; \
+AFFECTS_C_CPP=`python -c 'import os; \
+ import sys; \
sys.path.insert(0, "tools/run_tests/python_utils"); \
import filter_pull_request_tests as filter; \
- print(filter.affects_c_cpp("origin/$ghprbTargetBranch"))'`
+ github_target_branch = os.environ.get("ghprbTargetBranch"); \
+ print(filter.affects_c_cpp("origin/%s" % github_target_branch))'`
if [ $AFFECTS_C_CPP == "False" ] ; then
echo "This pull request does not affect C/C++. Tests do not need to be run."