Git revert guide

"I did git pull and my shit doesn't work"

Check the commit history with
git log -30 --format=format:"[%cr] %C(auto)%h %C(green)%aN%Creset %<(80,trunc)%s"
You can increase the number of commits shown by increasing the number in git log -30

git log output

The commit hash is shown in orange color.
If you remember when you last had a working build you can use:
git checkout COMMIT_HASH

For example if I wanted to revert back to the commit from 15 hours ago: git checkout 8561d57

You can also revert back by hours/days with:
git checkout @{two.hours.ago}
git checkout @{15.hours.ago}
git checkout @{one.day.ago}
git checkout @{two.days.ago}

When you eventually want to update you need to use:
git checkout master
git pull

How to prevent myself from getting stuck with an unstable build?

Before doing git pull run git rev-parse --short HEAD to get your current commit hash.
Save the string of characters it outputs.
Do git pull
If something doesn't work you can use git checkout HASH to revert to a previous version.