Fixed crash in iter api, triggered by calling index_update() on the loop py seq in the py api. Note, I didn't fix the underlying problem (bad iter type) so loops.index_update() still isn't working (it's just not crashing).

source/blender/bmesh/intern/bmesh_iterators_inline.h

@@ -161,10 +161,12 @@ BLI_INLINE int BM_iter_init(BMIter *iter, BMesh *bm, const char itype, void *dat
 			iter->edata = data;
 			break;
 		default:
+			return FALSE;
 			break;
 	}
 	
 	iter->begin(iter);
+
 	return TRUE;
 }