Hey there @theaussie86 – in my case it helped to do this:
nano /etc/shadow
Find the line with the git user on it, and if it has one or two exclamation marks in it, like so:
git:!:19425::::::
git:!!:19425::::::
then replace the ‘!‘/’!!’ with something else such as a *, et voilà, git push/pull/clone and everything else works again as smoothly as before. Some more context and detail: Update to 15.11.3 breaks ssh key access