v2.7.18: bugfix checking private key

lib/core.js

@@ -505,7 +505,7 @@ module.exports.create = function (gl) {
               return cert;
             } else {
               return gl.store.certificates.checkKeypairAsync(args).then(function (keypair) {
-                cert.privkey = RSA.exportPrivatePem(keypair).privateKeyPem;
+                cert.privkey = keypair.privateKeyPem || RSA.exportPrivatePem(keypair);
                 return cert;
               });
             }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "greenlock",
-  "version": "2.7.17",
+  "version": "2.7.18",
   "description": "Let's Encrypt for node.js on npm",
   "main": "index.js",
   "files": [