Remove special handling of neutral I-eliminations in unifier

src/Elab/Eval.hs

@@ -234,22 +234,6 @@ unify' topa topb = join $ go <$> forceIO topa <*> forceIO topb where
     | x == x', length a == length a' =
       traverse_ (uncurry unify'Spine) (Seq.zip a a')
 
-  go lhs@(VNe _hd (_ Seq.:|> PIElim _l x y i)) rhs =
-    case force i of
-      VI0 -> unify' x rhs
-      VI1 -> unify' y rhs
-      _   -> case rhs of
-        VSystem sys -> goSystem (flip unify') sys lhs
-        _ -> fail
-
-  go lhs rhs@(VNe _hd (_ Seq.:|> PIElim _l x y i)) =
-    case force i of
-      VI0 -> unify' lhs x
-      VI1 -> unify' lhs y
-      _   -> case lhs of
-        VSystem sys -> goSystem unify' sys rhs
-        _ -> fail
-
   go (VLam p (Closure _ k)) vl = do
     t <- VVar <$> newName
     unify' (k t) (vApp p vl t)