Request: enable cloning with --single-branch

[AndydeCleyre]

Hello, and thanks!

Sometimes repos have extra branches which take up extra space and bandwidth, for example for documentation websites. I'd like to be able to skip handling all that by checking out the repos with git clone's --single-branch option.

Three approaches I can think of, any of which would be great:

• Always use --single-branch
• Use --single-branch only when @branchname is used
• Use --single-branch when some new option to the load subcommand is used

[AndydeCleyre]

I'll add that an alternative solution would be a "degit" option like zimfw's.

[agkozak]

Thanks, @AndydeCleyre ! @sergiorussia has proposed using shallow (--depth 1) clones, and I've got an experimental branch depth1, but I've been holding off making it official because I haven't decided exactly how it should work yet. We made shallow clones the default behavior for now (almost all the time -- it's complex -- you can see the discussion), but plugin authors will want to be able to opt out of that.

Your --single-branch proposal seems closely related, the idea being just to download less stuff. I'll take it into account as I decide what to do next.

P.S. @zimfw's degit looks very clever!