fix: stop suggesting npm publish if package.json was not updated

lib/lifecycles/tag.js

@@ -1,3 +1,4 @@
+const bump = require('../lifecycles/bump')
 const chalk = require('chalk')
 const checkpoint = require('../checkpoint')
 const figures = require('figures')
@@ -27,7 +28,7 @@ function execTag (newVersion, pkgPrivate, args) {
   return runExec(args, 'git tag ' + tagOption + args.tagPrefix + newVersion + ' -m "' + formatCommitMessage(args.message, newVersion) + '"')
     .then(() => {
       let message = 'git push --follow-tags origin master'
-      if (pkgPrivate !== true) {
+      if (pkgPrivate !== true && bump.getUpdatedConfigs()['package.json']) {
         message += ' && npm publish'
         if (args.prerelease !== undefined) {
           if (args.prerelease === '') {

test.js

@@ -988,5 +988,12 @@ describe('standard-version', function () {
           output.stdout.should.include('v5.1.0')
         })
     })
+
+    it('does not display `npm publish` if there is no package.json', function () {
+      shell.rm('package.json')
+      var result = execCli()
+      result.code.should.equal(0)
+      result.stdout.should.not.match(/npm publish/)
+    })
   })
 })