extensions/git/src/commands.ts/CommandCenter/timelineCompareWithSelected
class CommandCenter:	async timelineCompareWithSelected(item: TimelineItem, uri: Uri | undefined, _source: string) {
		if (!GitTimelineItem.is(item) || !uri || !this._selectedForCompare || uri.toString() !== this._selectedForCompare.uri.toString()) {
			return;
		}

		const { item: selected } = this._selectedForCompare;

		const basename = path.basename(uri.fsPath);
		let leftTitle;
		if ((selected.previousRef === 'HEAD' || selected.previousRef === '~') && selected.ref === '') {
			leftTitle = localize('git.title.workingTree', '{0} (Working Tree)', basename);
		}
		else if (selected.previousRef === 'HEAD' && selected.ref === '~') {
			leftTitle = localize('git.title.index', '{0} (Index)', basename);
		} else {
			leftTitle = localize('git.title.ref', '{0} ({1})', basename, selected.shortRef);
		}

		let rightTitle;
		if ((item.previousRef === 'HEAD' || item.previousRef === '~') && item.ref === '') {
			rightTitle = localize('git.title.workingTree', '{0} (Working Tree)', basename);
		}
		else if (item.previousRef === 'HEAD' && item.ref === '~') {
			rightTitle = localize('git.title.index', '{0} (Index)', basename);
		} else {
			rightTitle = localize('git.title.ref', '{0} ({1})', basename, item.shortRef);
		}


		const title = localize('git.title.diff', '{0} ↔ {1}', leftTitle, rightTitle);
		await commands.executeCommand('vscode.diff', selected.ref === '' ? uri : toGitUri(uri, selected.ref), item.ref === '' ? uri : toGitUri(uri, item.ref), title);
	}