Bump Iris.

opam

@@ -9,6 +9,6 @@ build: [make "-j%{jobs}%"]
 install: [make "install"]
 remove: ["rm" "-rf" "%{lib}%/coq/user-contrib/iris_examples"]
 depends: [
-  "coq-iris" { (= "dev.2019-03-26.0.0495f119") | (= "dev") }
+  "coq-iris" { (= "dev.2019-04-07.4.4760ad33") | (= "dev") }
   "coq-autosubst" { = "dev.coq86" }
 ]

theories/logatom/treiber.v

@@ -9,7 +9,7 @@ Definition new_stack: val := λ: <>, ref (ref NONE).
 Definition push: val :=
   rec: "push" "s" "x" :=
       let: "hd" := !"s" in
-      let: "s'" := ref SOME ("x", "hd") in
+      let: "s'" := ref (SOME ("x", "hd")) in
       if: CAS "s" "hd" "s'"
         then #()
         else "push" "s" "x".