refresh GitView when git repo changes

- With current theia code, GitView could be initialised with incorrect repository, and it fails to change its internal state when the right repository is found. With this change, GitView is refreshed if and only if the active git repository changes.
- fixed #3988
- fixed #4219

Signed-off-by: elaihau <liang.huang@ericsson.com>

packages/git/src/browser/git-widget.tsx

@@ -17,6 +17,7 @@
 import { injectable, inject, postConstruct } from 'inversify';
 import URI from '@theia/core/lib/common/uri';
 import { ResourceProvider, CommandService, MenuPath } from '@theia/core';
+import { DisposableCollection } from '@theia/core/lib/common';
 import { ContextMenuRenderer, LabelProvider, DiffUris, StatefulWidget, Message, SELECTED_CLASS, Key, ConfirmDialog } from '@theia/core/lib/browser';
 import { EditorManager, EditorWidget, EditorOpenerOptions } from '@theia/editor/lib/browser';
 import { WorkspaceCommands } from '@theia/workspace/lib/browser';
@@ -53,6 +54,8 @@ export class GitWidget extends GitDiffWidget implements StatefulWidget {
     protected listContainer: GitChangesListContainer | undefined;
     protected readonly selectChange = (change: GitFileChangeNode) => this.selectNode(change);
 
+    protected readonly toDisposeOnInitialize = new DisposableCollection();
+
     @inject(EditorManager)
     protected readonly editorManager: EditorManager;
 
@@ -94,10 +97,11 @@ export class GitWidget extends GitDiffWidget implements StatefulWidget {
     }
 
     async initialize(repository: Repository | undefined): Promise<void> {
+        this.toDisposeOnInitialize.dispose();
         if (repository) {
-            this.toDispose.dispose();
-            this.toDispose.push(await this.gitWatcher.watchGitChanges(repository));
-            this.toDispose.push(this.gitWatcher.onGitEvent(async gitEvent => {
+            this.toDispose.push(this.toDisposeOnInitialize);
+            this.toDisposeOnInitialize.push(await this.gitWatcher.watchGitChanges(repository));
+            this.toDisposeOnInitialize.push(this.gitWatcher.onGitEvent(async gitEvent => {
                 if (GitStatusChangeEvent.is(gitEvent)) {
                     if (gitEvent.status.currentHead !== this.lastHead) {
                         this.lastHead = gitEvent.status.currentHead;