src/vs/platform/update/electron-main/abstractUpdateService.ts/AbstractUpdateService/isLatestVersion
class AbstractUpdateService:	async isLatestVersion(): Promise<boolean | undefined> {
		if (!this.url) {
			return undefined;
		} else if (this.getUpdateMode() === 'none') {
			return false;
		}

		const context = await this.requestService.request({ url: this.url }, CancellationToken.None);

		// The update server replies with 204 (No Content) when no
		// update is available - that's all we want to know.
		return context.res.statusCode === 204;
	}