abandon_stale: fix style warnings from flake8
abandon_stale: fix style warnings from flake8

Change-Id: I7d12bc2e9edc0fbbbb7e0aea61b4c7118d99fb2d

gerrit-review/gerrit,WANdisco/gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,gerrit-review/gerrit,qtproject/qtqa-gerrit,gerrit-review/gerrit,WANdisco/gerrit,gerrit-review/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,GerritCodeReview/gerrit,qtproject/qtqa-gerrit,qtproject/qtqa-gerrit,WANdisco/gerrit,GerritCodeReview/gerrit,WANdisco/gerrit,gerrit-review/gerrit,WANdisco/gerrit,qtproject/qtqa-gerrit,gerrit-review/gerrit,gerrit-review/gerrit,GerritCodeReview/gerrit