__iter__ functionality change in icetray

[Samhori]

The first major change in https://github.com/icecube/icetray/pull/3576 changed how iter functioned. As a result {i[0]: i[1].position for i in geo_map if i[1].omtype.name == 'IceCube'} in Geometry throws an error.

Reverting to an earlier version of icetray prior to this change is a temporary workaround.