chore: add fixed test case for #9363 (#10547)

Author: sgraf812

tests/lean/run/9363.lean

@@ -0,0 +1,44 @@
+import Std.Tactic.Do
+
+open Std.Do
+
+set_option mvcgen.warning false
+
+axiom P : Nat → Prop
+axiom P' : Nat → Prop
+axiom Q : Nat → Prop
+axiom R : Assertion ps
+
+axiom hPQ : ∀ n, P n → P' n → Q n
+
+axiom G : StateM Nat Unit
+axiom H : StateM Nat Unit
+
+noncomputable def F : StateM Nat Unit := do
+  G
+  H
+
+@[spec]
+axiom G_spec : ⦃⌜True⌝⦄ G ⦃⇓ _ n => ⌜P n ∧ P' n⌝⦄
+
+@[spec]
+axiom H_spec : ⦃fun n => ⌜Q n⌝⦄ H ⦃⇓ _ => R⦄
+
+theorem F_spec :
+   ⦃⌜True⌝⦄
+   F
+   ⦃⇓ _ => R⦄ := by
+  mvcgen [F]
+
+  -- Goal:
+  -- s✝¹ : Nat
+  -- r✝ : Unit
+  -- s✝ : Nat
+  -- h : P s✝ ∧ P' s✝
+  -- ⊢ Q s✝
+
+  rename_i h
+  cases h
+  apply hPQ
+  assumption
+  assumption