Adding any file to gitignore prompts to reload any notebook with unsaved changes

[ianhi]

Description

If you add a file to the gitignore while you have any files open that have unsaved changes then the UI will prompt you to reload those files. This will throw away unsaved changes to files that were not involved in the git action.

I think the jupyterlab warning is a bit unclear here as to which notebook is going to be reloaded. Which then makes this a dangerously easy way for someone to lose unsaved work.

This is caused by these lines:

jupyterlab-git/src/commandsAndMenu.ts

Lines 203 to 206 in 7f3e4cc

	await gitModel.commands.execute('docmanager:reload');
	await gitModel.commands.execute('docmanager:open', {
	path: model.getRelativeFilePath('.gitignore')
	});

Which I think are run to ensure that an updated .gitignore file is displayed. @echarles is this the correct reason for the docmanager:reload?

I think we can get the same effect without the reload by reverting the file similar to here:

jupyterlab-git/src/model.ts

Lines 1432 to 1437 in 7f3e4cc

	private _revertFile(path: string): void {
	const widget = this._docmanager.findWidget(this.getRelativeFilePath(path));
	if (widget && !widget.context.model.dirty) {
	widget.context.revert();
	}
	}

Reproduce

1. Have an open notebook with unsaved changes
2. add any file to gitignore
3. see prompt asking you to reload notebook
4. if you click reload all unsaved changes will be lost

Expected behavior

Context

• Python package version: 0.21.0

• Extension version: 0.21.0

• Git version: 2.25.1

• Operating System and its version: PopOS 20.04

Command Line Output

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