extensions/git/src/timelineProvider.ts/GitTimelineItem/shortenRef
class GitTimelineItem:	private shortenRef(ref: string): string {
		if (ref === '' || ref === '~' || ref === 'HEAD') {
			return ref;
		}
		return ref.endsWith('^') ? `${ref.substr(0, 8)}^` : ref.substr(0, 8);
	}