Tido.com [1] filed a orphan request for redmine [2]:

I would be willing to adopt this package

Over 5 weeks since the release (2015-03-16)
Over 4 weeks since it was flagged out of date (2015-03-20)

[1] https://aur.archlinux.org/account/Tido.com/
[2] https://aur.archlinux.org/pkgbase/redmine/