It can stop you, but odds are it doesn't in many cases. IMO this is one of the biggest benefits of git over something like Subversion or CVS: its distributed, so you can continue to work locally while the origin is unreachable.
I can't tell you how many times in my svn past where I couldn't get any work done simply as a result of the repo sever going down or having some other issue affecting its reachability.
At least with git I may not be able to pull commits from origin, but I can still commit locally which is typically enough to keep me productive during outage periods.
It's certainly better than a similarly stable SVN server, there's no question about that.
However, when it's down, I can't push my changes for others to review, or review pull requests. I can't update and pull in the latest changes, or checkout branches to help someone with a bug. If it's an integral part of your workflow, it can be quite a pain when it's down.
"I can't tell you how many times in my svn past where I couldn't get any work done simply as a result of the repo sever going down or having some other issue affecting its reachability."
I had the opposite experience, although an SVN outage would have been worse, I'm used to them being far rarer.
", I can't push my changes for others to review, or review pull requests. I can't update and pull in the latest changes, or checkout branches to help someone with a bug"
You can do all of these things if your colleague has that branch checked out - it does require remembering some pretty poorly-named CLI flags though!
Maybe, I work remotely, most other people will be in the office. Pulling something from someone on the internal network might be... interesting.
It is another benefit of git, and one of the reasons I first moved to it (often did work on a robotic system, pulling an pushing new branches was a really nice way of moving code back and forth without committing to a central repo).
Git is great, and github is brilliant. I just wish it was more stable, because I would say that is a real issue at the moment.
I can't tell you how many times in my svn past where I couldn't get any work done simply as a result of the repo sever going down or having some other issue affecting its reachability.
At least with git I may not be able to pull commits from origin, but I can still commit locally which is typically enough to keep me productive during outage periods.