Fix the setting of REPL namespace

We used to set the ns before switching the to ns buffer, but that's
no longer correct after the introduction of smart REPL selection.
The ns has to be set after you've switched to the right REPL buffer.

cider-interaction.el

@@ -440,11 +440,13 @@ When SET-NAMESPACE is t, sets the namespace in the REPL buffer to
 that of the namespace in the Clojure source buffer."
   (cider-ensure-connected)
   (let ((buffer (current-buffer)))
-    (when set-namespace
-      (cider-repl-set-ns (cider-current-ns)))
+    ;; first we switch to the REPL buffer
     (if cider-repl-display-in-current-window
         (pop-to-buffer-same-window repl-buffer)
       (pop-to-buffer repl-buffer))
+    ;; then if necessary we update its namespace
+    (when set-namespace
+      (cider-repl-set-ns (with-current-buffer buffer (cider-current-ns))))
     (cider-remember-clojure-buffer buffer)
     (goto-char (point-max))))