Make sure monger.collection/insert-and-return respects existing document id, just like save-and-return does

src/clojure/monger/collection.clj

@@ -97,7 +97,7 @@
      ;; and it does not work very well in our case, because that DBObject is short lived and produced
      ;; from the Clojure map we are passing in. Plus, this approach is very awkward with immutable data
      ;; structures being the default. MK.
-     (let [doc (merge document {:_id (ObjectId.)})]
+     (let [doc (merge {:_id (ObjectId.)} document)]
        (insert db collection doc concern)
        doc)))
 

test/monger/test/inserting_test.clj

@@ -129,6 +129,13 @@
     (is (:_id result))
     (is (= 1 (mc/count collection)))))
 
+(deftest  insert-and-return-with-a-provided-id
+  (let [collection "people"
+        oid        (ObjectId.)
+        doc        {:name "Joe" :age 30 :_id oid}
+        result     (mc/insert-and-return :people doc)]
+    (is (= (:_id result) (:_id doc) oid))
+    (is (= 1 (mc/count collection)))))
 
 
 ;;