fix(vscode-github): current branch detection

Author: KnisterPeter

src/git.ts

@@ -14,7 +14,7 @@ export async function getGitHubOwnerAndRepository(cwd: string): Promise<string[]
 export async function getCurrentBranch(cwd: string): Promise<string|undefined> {
   return execa('git', ['status', '--porcelain', '--branch'], {cwd})
     .then(result => {
-      const match = result.stdout.match(/^## (.+?)(?:\.\.\..*)?/);
+      const match = result.stdout.match(/^## ([^.]+)(?:\.\.\..*)?/);
       return match ? match[1] : undefined;
     });
 }