Thinking out loud…
Generally they're under tension, the process of bending it means it must be stretched further to its new location (straight is the shortest run obviously) so in order for it to be bent it must plastically deform. As it's already in tension and the bend is likely to be fairly large radius (relative to diam) it's main constituent is going to be plastic deformation on the outside of the bend, in tension and probably on the inside too. Once that deformation has happened the spoke will relax back down the elastic load line (as if it were never plastically deformed) but now it's fractionally longer (at least on one side) so assuming the end points are fixed it will now be under less tension as some of the strain was absorbed by the plastic deformation. But, and I think this is where you were thinking, there's now a bend which means there's extra length to make up and if it had not deformed plastically it would now be under much more tension, but without fairly large Pdeformation it would just spring back into linear shape, but maybe the balance is dependent on the type of bend and other factors.
I'd need to think it over when I'm in a more analytical frame of mind to be sure of myself.
Just a thought, and matches my personal experience when I've bent spokes.
