add git-sync

[kumon]

This command syncs local branch with remote branch.

This runs:

git fetch <remote-name> <branch-name>
git reset --hard <remote-name>/<branch-name>
git clean -d -f -x

[spacewander]

help can be a legal name of a remote branch.

[kumon]

Thank you for reviewing it. I should fix that.

[nicolaiskogheim]

As we don't use "?" for seeing usage with any other commands, we shouldn't do it here either.
? is a special character in some terminals with extglob (i think) enabled, and could confuse people as well.

[kumon]

I will remove '?'. Thank you!

[spacewander]

What about using a default remote/branch when remote/branch argument is missing?
Just follow the convention of git fetch/pull.

[kumon]

I will follow the convention of git fetch/pull. It's more practical. Thank you so much.

[kumon]

I changed to use upstream of local branch by default, when remote/branch is not specified.

[spacewander]

A little quibble:
git rev-parse --abbrev-ref --symbolic-full-name @{u} will return nothing if there is not related upstream branch.
Then users will see ... & sync with ''? [y/N] and the command may simply reset to current branch, which is not really wanted.

[kumon]

I added upstream check that is based on exit status of git rev-parse --abbrev-ref --symbolic-full-name @{u}.

[spacewander]

@hemanth @qw3rtman
It looks good to me. What about your idea?

[qw3rtman]

Yup, looks good to me! Merging.

In the future, I think it'd be a good idea to standardize how help/usage is displayed for each command. Each command should have the same name for the function that displays the help/usage. Additionally, the formatting of the usage should be the same.

[kumon]

Thank you for reviewing it!

[qw3rtman]

Thanks for contributing, @kumon! 😄