Get rid of the unnecessary `iNext`

F_mu_ref_conc/proofmode/rel_tactics.v

@@ -144,7 +144,7 @@ Tactic Notation "rel_pure_r" open_constr(ef) :=
       |try (exact I || reflexivity || tac_rel_done)  (* φ *)
       |solve_ndisj                 (* ↑specN ⊆ E1 *)
       |simpl; reflexivity          (* eres = fill K e2 *)
-      |try iNext; simpl_subst/=    (* new goal *)])
+      |simpl_subst/=               (* new goal *)])
   || fail "rel_pure_r: cannot find the reduct".
 
 Tactic Notation "rel_rec_r" := rel_pure_r (App (Rec _ _ _) _) || rel_pure_r (App _ _).