The magnet.protocol file isn't being installed. It seems that enabling KIO_MAGNET is required. I added the following to my ktorrent-9999.ebuild: -DENABLE_KIO_MAGNET=ON in the list of mycmakeargs, and then magnet links worked. I'm not sure if this is actually supposed to be supplied elsewhere, but without this, magnet links weren't working for me. (Using KDE 4.10.2) Reproducible: Always
Magnet KIO is removed by upstream. https://projects.kde.org/projects/extragear/network/ktorrent/repository/revisions/09547eac0eb81dbb3c5f93e3c7df68473a30e0f6