[snowpatch] [PATCH] main, git: Rework creation of patch branch

[Russell Currey]

On Wed, 2019-07-10 at 11:05 +1000, Andrew Donnellan wrote:
> When we update our remote tracking branch after the remote branch has
> been
> rebased, using git pull will result in a merge commit being created,
> which
> is not the behaviour we want.
> 
> Instead, fetch the remote, and create our new patch application
> branch
> directly, without checking out a remote tracking branch and pulling.
> This
> is a lot cleaner. Add a few helper functions to facilitate this.
> 
> This requires a new project config option, base_remote_name, to
> specify the
> name of the remote from which we are fetching base branches. If not
> specified, it will default to the same remote to which we are
> pushing. This
> is a breaking change and will require existing users to update their
> configuration.
> 
> Signed-off-by: Andrew Donnellan <ajd at linux.ibm.com>

Looks good - maybe we should give a warning if it's not specified
though, users can avoid the warning by specifying the config option,
and avoids people potentially not getting the behaviour they expect.