extensions/git/src/commands.ts/CommandCenter/runGitMerge
class CommandCenter:	private async runGitMerge(diff3: boolean): Promise<void> {
		const { activeTab } = window.tabGroups.activeTabGroup;
		if (!activeTab) {
			return;
		}

		const input = activeTab.input;
		if (!(input instanceof TabInputTextMerge)) {
			return;
		}

		const result = await this.git.mergeFile({
			basePath: input.base.fsPath,
			input1Path: input.input1.fsPath,
			input2Path: input.input2.fsPath,
			diff3,
		});

		const doc = workspace.textDocuments.find(doc => doc.uri.toString() === input.result.toString());
		if (!doc) {
			return;
		}
		const e = new WorkspaceEdit();

		e.replace(
			input.result,
			new Range(
				new Position(0, 0),
				new Position(doc.lineCount, 0),
			),
			result
		);
		await workspace.applyEdit(e);
	}