Felix> Bugzilla looks old, but works. +1 I'm not sure if migrating to JIRA would attract more users/developers.
I'm not sure if Apache has mailing archive support for GitHub issues. Plain "GitHub issues" are not searchable (one does not simply find a GitHub issue in Google due to https://github.com/robots.txt ), so a sophisticated archiving of the comments should be installed. There's on-going issue for "mailing list support" for Gitlab: https://gitlab.com/gitlab-org/gitlab-ce/issues/4272 Vladimir
