New fetch can override local changes without warning

[josephjclark]

I'm going to push the new fetch command through but there may be an issue that requires priority investigation.

When making changes to a local project file, if you run fetch, the remote version will override the local version without warning.

But really I expect a conflict. The local version's head should be a version hash that does not exist in the remote. It would be lost in the merge and therefore should warn.

Here's how I just saw this:

• Pull a project
• Edit an expression in the local yaml
• Pull the project again (just repeat the command)
• I expect an error but none is forthcoming
• the local edit is lost

I don't think this is super important because you shouldn't be edting a local yaml anyway. It might become more important when resolving conflicts