CLJS-3273 preserve ns-name when processing an :ns* op

This happens when a namespace contains both an `ns` form and a `require`
statement. The `require` will expand to `(ns* (require ...))`, and when
processed will generate a namespace name of the form `cljs.user.*` which ends up
replacing the ns-name set in the `ns` declaration.

src/main/clojure/cljs/compiler.cljc

@@ -1564,7 +1564,9 @@
 
                      (= :ns* (:op ast))
                      (let [ns-emitted? (some? ns-name)
-                           ns-name (ana/gen-user-ns src)]
+                           ns-name (if-not ns-emitted?
+                                     (ana/gen-user-ns src)
+                                     ns-name)]
                        (if-not ns-emitted?
                          (emit (assoc ast :name ns-name :op :ns))
                          (emit ast))

src/test/clojure/cljs/compiler_tests.clj

@@ -358,6 +358,14 @@
                      (def hist (Html5History.))]))
                "(new goog.history.Html5History());"))))
 
+(deftest emit-source-ns*-retains-ns-name ;; CLJS-3273
+  (let [input   (java.io.File/createTempFile "foo" ".cljs")
+        output  (java.io.File/createTempFile "foo" ".js")
+        _       (spit input "(ns foo.foo) (require 'clojure.string)")
+        ns-info (env/ensure (comp/emit-source input output "cljs" {}))]
+    (is (= 'foo.foo (:ns ns-info)))))
+
+
 ;; CLJS-1225
 
 (comment