Implement upstream Git Cola update detection.

[Vdragon]

Hi Git Cola developers!
It would be great if Git Cola supports detecting new releases from GitHub on Git Cola(in case that user build the software without using any maintained software sources).

[kkofler]

The problem with this RFE is that, as a packager, I explicitly DON'T want this. I don't want my users to get notified of updates that are not yet available to them.

[Vdragon]

@kkofler Make an option to disable this feature?

[davvid]

I manage my git-cola installs at $dayjob using the distro-provided package manager and homegrown pacakges, so I wouldn't really use this feature myself. But, it is pretty easy to implement a custom guitool command that provides this feature if someone really wanted it.

Add the following to .gitconfig:

[guitool "Update git-cola"]
    cmd = git-cola-update

And provide a ~/bin/git-cola-update shell script:

#!/bin/sh
cd "$HOME/src/git-cola" &&
git fetch origin &&
git rebase origin/master

This will make an "Update git-cola" action appear in the Actions menu. It's not quite automatic, but at least it's only a few clicks away.