fix issue with re-require()'ing native modules

Discussion on why this change was required can be found in the following issues:

jestjs/jest#3552
jestjs/jest#3550
nodejs/node#5016

generate/templates/templates/nodegit.js

@@ -1,3 +1,4 @@
+var _ = require("lodash");
 var promisify = require("promisify-node");
 var rawApi;
 
@@ -15,6 +16,12 @@ catch (ex) {
   rawApi = require("../build/Debug/nodegit.node");
 }
 
+// For disccussion on why `cloneDeep` is required, see:
+// https://github.com/facebook/jest/issues/3552
+// https://github.com/facebook/jest/issues/3550
+// https://github.com/nodejs/node/issues/5016
+rawApi = _.cloneDeep(rawApi);
+
 // Native methods do not return an identifiable function, so we
 // have to override them here
 /* jshint ignore:start */

lib/revwalk.js

@@ -2,7 +2,8 @@ var NodeGit = require("../");
 var Revwalk = NodeGit.Revwalk;
 
 Object.defineProperty(Revwalk.prototype, "repo", {
-  get: function () { return this.repository(); }
+  get: function () { return this.repository(); },
+  configurable: true
 });
 
 var _sorting = Revwalk.prototype.sorting;