Bump std++.

opam

@@ -12,5 +12,5 @@ remove: ["rm" "-rf" "%{lib}%/coq/user-contrib/iris"]
 depends: [
   "coq" { >= "8.6.1" & < "8.8~" }
   "coq-mathcomp-ssreflect" { (>= "1.6.1" & < "1.7~") | (= "dev") }
-  "coq-stdpp" { (= "dev.2017-10-28.0") | (= "dev") }
+  "coq-stdpp" { (= "dev.2017-10-28.3") | (= "dev") }
 ]

theories/proofmode/environments.v

@@ -150,7 +150,7 @@ Proof.
 Qed.
 
 Lemma env_lookup_delete_correct Γ i :
-  env_lookup_delete i Γ = x ← Γ !! i; Some (x,env_delete i Γ).
+  env_lookup_delete i Γ = (x ← Γ !! i; Some (x,env_delete i Γ)).
 Proof. induction Γ; intros; simplify; eauto. Qed.
 Lemma env_lookup_delete_Some Γ Γ' i x :
   env_lookup_delete i Γ = Some (x,Γ') ↔ Γ !! i = Some x ∧ Γ' = env_delete i Γ.