CI: flake8: adjust for 'pmbootstrap ci' (MR 3615)

.ci/flake8.sh

+#!/bin/sh -e
+# Description: lint CI related python scripts/tests
+# https://postmarktos.org/pmb-ci
+
+if [ "$(id -u)" = 0 ]; then
+	set -x
+	apk -q add py3-flake8
+	exec su "${TESTUSER:-build}" -c "sh -e $0"
+fi
+
+set -x
+
+# shellcheck disable=SC2046
+flake8 --ignore E501,F401,E722,W504,W605 $(find .ci -name '*.py')

.gitlab-ci.yml

@@ -36,7 +36,7 @@ wiki:
     - .ci/wiki.sh
 
 # testcases linting
-testcases-linting:
+flake8:
   stage: lint
   <<: *only-default
   only:
@@ -48,7 +48,8 @@ testcases-linting:
   before_script:
     - apk -q add py-flake8
   script:
-    - flake8 --ignore E501,F401,E722,W504,W605
+    - .ci/lib/gitlab_prepare_ci.sh
+    - .ci/flake8.sh
 
 # shellcheck
 shellcheck: