"Unable to connect to Upstart" error when installing git-all

It's happening because of this bug https://bugs.launchpad.net/ubuntu/+source/runit/+bug/1448164

You need to remove runit and git-daemon-run. That should fix the problem.

sudo apt-get purge runit git-daemon-run

Don't forget to visit the bug report and clicking Yes, this bug affects me.

git-all without error

It seems you can have git-all with daemon support without failing on this error. git-all recommends either git-daemon-run or git-daemon-sysvinit package. apt was choosing git-daemon-run as first choice. But If you explicitly mention the package you want (i.e git-daemon-sysvinit), apt won't try to install git-daemon-run.

All you need to do is

sudo apt-get install git-all git-daemon-sysvinit

Hope that helps.

You'll need to forcibly remove runit. Running sudo dpkg -r runit should work. You might need to use one of the --force-* options.

Try:

sudo apt update 
sudo apt --purge remove git 
sudo apt install git

instead.