Pin isort to fix sanity test breakage
diff --git a/tools/distrib/pylint_code.sh b/tools/distrib/pylint_code.sh
index 5e6b818..060c2b7 100755
--- a/tools/distrib/pylint_code.sh
+++ b/tools/distrib/pylint_code.sh
@@ -40,7 +40,9 @@
PYTHON=$VIRTUALENV/bin/python
$PYTHON -m pip install --upgrade pip==19.3.1
-$PYTHON -m pip install --upgrade astroid==2.3.3 pylint==2.2.2
+
+# TODO(https://github.com/grpc/grpc/issues/23394): Update Pylint.
+$PYTHON -m pip install --upgrade astroid==2.3.3 pylint==2.2.2 "isort>=4.3.0,<5.0.0"
EXIT=0
for dir in "${DIRS[@]}"; do