feat: detect external pull request and allow to pull it

This case enables external pull requests (from forked repo
without write permission) to be checked out for review.
For security reasons the user needs to confirm to pull
external code (it could be harmful to pull code if watch
tasks are running over external code).

Closes #258

Author: KnisterPeter

src/commands/pull-requests.ts

@@ -281,6 +281,22 @@ export class Git {
     }
   }
 
+  public async branch(
+    name: string,
+    base: string,
+    uri: vscode.Uri
+  ): Promise<void> {
+    await this.execute(`git checkout -b ${name} ${base}`, uri);
+  }
+
+  public async pullExternal(
+    repositoryUrl: string,
+    branch: string,
+    uri: vscode.Uri
+  ): Promise<void> {
+    await this.execute(`git pull ${repositoryUrl} ${branch}`, uri);
+  }
+
   private logAndShowError(e: Error): void {
     if (this.channel) {
       this.channel.appendLine(e.message);