src/vs/workbench/services/search/node/fileSearch.ts/FileWalker/readStdout
class FileWalker:	readStdout(cmd: childProcess.ChildProcess, encoding: BufferEncoding, cb: (err: Error | null, stdout?: string) => void): void {
		let all = '';
		this.collectStdout(cmd, encoding, () => { }, (err: Error | null, stdout?: string, last?: boolean) => {
			if (err) {
				cb(err);
				return;
			}

			all += stdout;
			if (last) {
				cb(null, all);
			}
		});
	}