Add new "copy group" command

[worksWithTools]

Use case:

I have many repositories under my git meta-repo. I have created a set of "default" groups that I use to create easy to remember groups that represent certain recurring activities. e.g. group list: new : group with repos most frequently occurring in "new feature" work bug_fix : group with repos most frequently occurring in "bug fix" work

I have found as I worked with this that sometimes the requirements change, and I want to add repos to the current working group. However, I don't want to make the change permanent, so I really just want to make a new group based on an existing group and make changes to that. Up til now, I've been doing it by hand editing the .mu_repo file, but I though maybe I could add a small feature to mu_repo that makes copying an existing repo an option.

usage: mu group copy

example: mu group copy new copy_group_feature

would take the existing "new" group and copy it into a new group called "copy_group_feature"

Unit Tests updated to reflect new feature.

[fabioz]

Humm, if you're in the group you want, mu group add will actually already copy that group over the new group (unless --empty is given)...

How about instead of doing a new command this becomes a flag of mu group add (there's already --empty to create an empty group, so, there could be a mu group add <group_name> --copy=<group_name_to_copy>)?

[worksWithTools]

Good idea - I'll take a look (There's actually a bug in my existing impl. anyway...)

[fabioz]

Can you also update the docs? i.e.: https://github.com/fabioz/mu-repo/blob/master/mu_repo/__docs__.py#L43

(you can just execute mu so that it prints it locally to see the output).

[worksWithTools]

Sure - will do.

[worksWithTools]

Sure - will do.

Done.

[fabioz]

Just merged. Thanks for the patch.