Fix crash when tapping the top right button for a merge event.
Fix crash when tapping the top right button for a merge event.

A merge event shows up as ForkApplyEvent in the Atom feed.  Since
the code does a prefix search, these events were wrongly matched
as ForkEvent instead.  Move the ForkApplyEvent code up to avoid
this bug.

dazuiba/flownbird,dazuiba/ioctocat