src/vs/platform/extensionManagement/common/extensionGalleryService.ts/isPreReleaseVersion
function isPreReleaseVersion(version: IRawGalleryExtensionVersion): boolean {
	const values = version.properties ? version.properties.filter(p => p.key === PropertyType.PreRelease) : [];
	return values.length > 0 && values[0].value === 'true';
}