src/vs/platform/extensionManagement/node/extensionDownloader.ts/ExtensionsDownloader/downloadSignatureArchive
class ExtensionsDownloader:	private async downloadSignatureArchive(extension: IGalleryExtension): Promise<URI> {
		await this.cleanUpPromise;

		const location = joinPath(this.extensionsDownloadDir, `${this.getName(extension)}${ExtensionsDownloader.SignatureArchiveExtension}`);
		await this.downloadFile(extension, location, location => this.extensionGalleryService.downloadSignatureArchive(extension, location));
		return location;
	}