mozilla/amo-validator — pull request #261 by olivier-m (2014-12-02 10:34:21+00:00)
Title: Issue a warning when add-on is already signed. (bug 1070188)

I added a test to check if an add-on has a preexisting signature.
See: https://bugzilla.mozilla.org/show_bug.cgi?id=1070188

The test only checks the presence of signature files, not their contents.