Update default branch in contributors graph

Updated the default branch to whatever is set on the project

app/assets/javascripts/contributors/index.js

 import Vue from 'vue';
 import ContributorsGraphs from './components/contributors.vue';
-import store from './stores';
+import { createStore } from './stores';
 
 export default () => {
   const el = document.querySelector('.js-contributors-graph');
 
   if (!el) return null;
 
+  const { projectGraphPath, projectBranch, defaultBranch } = el.dataset;
+  const store = createStore(defaultBranch);
+
   return new Vue({
     el,
     store,
@@ -14,8 +17,8 @@ export default () => {
     render(createElement) {
       return createElement(ContributorsGraphs, {
         props: {
-          endpoint: el.dataset.projectGraphPath,
-          branch: el.dataset.projectBranch,
+          endpoint: projectGraphPath,
+          branch: projectBranch,
         },
       });
     },

app/assets/javascripts/contributors/stores/index.js

@@ -7,12 +7,12 @@ import state from './state';
 
 Vue.use(Vuex);
 
-export const createStore = () =>
+export const createStore = (defaultBranch) =>
   new Vuex.Store({
     actions,
     mutations,
     getters,
-    state: state(),
+    state: state(defaultBranch),
   });
 
-export default createStore();
+export default createStore;

app/assets/javascripts/contributors/stores/state.js

-export default () => ({
+export default (branch) => ({
   loading: false,
   chartData: null,
-  branch: 'master',
+  branch,
 });

app/views/projects/graphs/show.html.haml

@@ -5,4 +5,4 @@
     = render 'shared/ref_switcher', destination: 'graphs'
   = link_to s_('Commits|History'), project_commits_path(@project, current_ref), class: 'btn gl-button btn-default'
 
-.js-contributors-graph{ class: container_class, 'data-project-graph-path': project_graph_path(@project, current_ref, format: :json), 'data-project-branch': current_ref }
+.js-contributors-graph{ class: container_class, data: { project_graph_path: project_graph_path(@project, current_ref, format: :json), project_branch: current_ref, default_branch: @project.default_branch } }