fix(code/frontend): HEAD should be default branch in branch selector (#40832) (#40837)

Author: WangQianliang

x-pack/legacy/plugins/code/public/components/main/content.tsx

@@ -20,6 +20,7 @@ import {
   SearchOptions,
   SearchScope,
   WorkerReservedProgress,
+  Repository,
 } from '../../../model';
 import { CommitInfo, ReferenceInfo } from '../../../model/commit';
 import { changeSearchScope, FetchFileResponse, RepoState, RepoStatus } from '../../actions';
@@ -57,6 +58,7 @@ interface Props extends RouteComponentProps<MainRouteParams> {
   fileTreeLoadingPaths: string[];
   searchOptions: SearchOptions;
   query: string;
+  currentRepository: Repository;
 }
 const LANG_MD = 'markdown';
 
@@ -232,6 +234,7 @@ class CodeContent extends React.PureComponent<Props> {
           searchOptions={this.props.searchOptions}
           branches={this.props.branches}
           query={this.props.query}
+          currentRepository={this.props.currentRepository}
         />
         {this.renderContent()}
       </div>
@@ -402,6 +405,7 @@ const mapStateToProps = (state: RootState) => ({
   repoStatus: statusSelector(state, repoUriSelector(state)),
   searchOptions: state.search.searchOptions,
   query: state.search.query,
+  currentRepository: state.repository.repository,
 });
 
 const mapDispatchToProps = {

x-pack/legacy/plugins/code/public/components/main/top_bar.tsx

@@ -6,7 +6,7 @@
 
 import { EuiFlexGroup, EuiFlexItem, EuiSelect } from '@elastic/eui';
 import React, { ChangeEvent } from 'react';
-import { SearchOptions, SearchScope } from '../../../model';
+import { SearchOptions, SearchScope, Repository } from '../../../model';
 import { ReferenceInfo } from '../../../model/commit';
 import { MainRouteParams } from '../../common/types';
 import { encodeRevisionString, decodeRevisionString } from '../../../common/uri_util';
@@ -22,6 +22,7 @@ interface Props {
   searchOptions: SearchOptions;
   branches: ReferenceInfo[];
   query: string;
+  currentRepository?: Repository;
 }
 
 export class TopBar extends React.Component<Props, { value: string }> {
@@ -38,6 +39,9 @@ export class TopBar extends React.Component<Props, { value: string }> {
 
   getBranch = (revision: string) => {
     const r = decodeRevisionString(revision);
+    if (r.toUpperCase() === 'HEAD' && this.props.currentRepository) {
+      return this.props.currentRepository.defaultBranch;
+    }
     const branch = this.props.branches.find(b => b.name === r);
     if (branch) {
       return branch.name;