macOS fix: Check for correct version of flake8 to avoid spurious warnings. The brew installed flake8 version is Python 2 based and does not work.

test/lint/lint-python.sh

@@ -79,4 +79,12 @@ export LC_ALL=C
 # W605 invalid escape sequence "x"
 # W606 'async' and 'await' are reserved keywords starting with Python 3.7
 
-flake8 --ignore=B,C,E,F,I,N,W --select=E101,E112,E113,E115,E116,E125,E129,E131,E133,E223,E224,E242,E266,E271,E272,E273,E274,E275,E304,E306,E401,E402,E502,E701,E702,E703,E714,E721,E741,E742,E743,E901,E902,F401,F402,F403,F404,F405,F406,F407,F601,F602,F621,F622,F631,F701,F702,F703,F704,F705,F706,F707,F811,F812,F821,F822,F823,F831,F841,W191,W291,W292,W293,W504,W601,W602,W603,W604,W605,W606 .
+if ! command -v flake8 > /dev/null; then
+    echo "Skipping Python linting since flake8 is not installed. Install by running \"pip3 install flake8\""
+    exit 0
+elif PYTHONWARNINGS="ignore" flake8 --version | grep -q "Python 2"; then
+    echo "Skipping Python linting since flake8 is running under Python 2. Install the Python 3 version of flake8 by running \"pip3 install flake8\""
+    exit 0
+fi
+
+PYTHONWARNINGS="ignore" flake8 --ignore=B,C,E,F,I,N,W --select=E101,E112,E113,E115,E116,E125,E129,E131,E133,E223,E224,E242,E266,E271,E272,E273,E274,E275,E304,E306,E401,E402,E502,E701,E702,E703,E714,E721,E741,E742,E743,E901,E902,F401,F402,F403,F404,F405,F406,F407,F601,F602,F621,F622,F631,F701,F702,F703,F704,F705,F706,F707,F811,F812,F821,F822,F823,F831,F841,W191,W291,W292,W293,W504,W601,W602,W603,W604,W605,W606 .