extensions/git/src/repository.ts/Repository/headShortName
class Repository:	get headShortName(): string | undefined {
		if (!this.HEAD) {
			return;
		}

		const HEAD = this.HEAD;

		if (HEAD.name) {
			return HEAD.name;
		}

		const tag = this.refs.filter(iref => iref.type === RefType.Tag && iref.commit === HEAD.commit)[0];
		const tagName = tag && tag.name;

		if (tagName) {
			return tagName;
		}

		return (HEAD.commit || '').substr(0, 8);
	}