Deleted try: except: ATM, this method seems is not need.
-After more test, this part working fine without errors.
This code is was update for me, very time ago with the first versions
of YafaRay integration in Blender 2.5 in not more stable state.

-Added texture projection options to "world panel" for improve it the work flow
Reverse this commit, if is 'source' of users errors.
-Disable "gamma_encode" and "clamp_rgb" options for sunsky2, changed int the last fix of DarkTide.