Add pyflakes3 target and script

Makefile

@@ -7,6 +7,7 @@ PYTHONPATH=$(shell pwd):$(shell pwd)/probert
 PROBERTDIR=./probert
 PROBERT_REPO=https://github.com/CanonicalLtd/probert
 export PYTHONPATH
+CWD := $(shell pwd)
 
 ifneq (,$(MACHINE))
 	MACHARGS=--machine=$(MACHINE)
@@ -39,6 +40,10 @@ lint:
 	python3 /usr/bin/flake8 bin/$(PYTHONSRC)-tui --ignore=F403
 	python3 /usr/bin/flake8 --exclude $(PYTHONSRC)/tests/ $(PYTHONSRC) --ignore=F403
 
+pyflakes3:
+	echo "Running pyflakes tests..."
+	@$(CWD)/scripts/run-pyflakes3
+
 unit:
 	echo "Running unit tests..."
 	nosetests3 $(PYTHONSRC)/tests

scripts/run-pyflakes3

@@ -0,0 +1,24 @@
+#!/bin/bash
+# This file is part of curtin. See LICENSE file for copyright and license info.
+
+#    "console_conf/"
+pycheck_dirs=(
+    "subiquity/"
+    "subiquitycore/"
+    "tests/"
+)
+
+set -f
+if [ $# -eq 0 ]; then
+   files=( "${pycheck_dirs[@]}" )
+else
+   files=( "$@" )
+fi
+
+cmd=( "python3" -m "pyflakes" "${files[@]}" )
+
+echo "Running: " "${cmd[@]}" 1>&2
+export PYFLAKES_BUILTINS="_"
+exec "${cmd[@]}"
+
+# vi: ts=4 expandtab syntax=sh