How can I do a bugfix on master and integrate it into my less stable branch(es)?

This is a classic case in which you can take advantage of Git branches. Here is the workflow you should use.

Let's say you've created a develop branch stemming from master and you've made a few commits on that branch:

Suddenly, you realise that there is a bug on master, a bug which you need to fix quickly. Instead of working directly off of master, you should create a short-lived bug-fix branch, to isolate the bug-fixing task from your master branch:

git checkout master
git checkout -b bugfix

After making one commit (or more) on the bugfix branch to fix the problem,

you should make sure that everything works as it should (run tests, etc.). When you're happy with the state of your code on bugfix, merge it into master:

git checkout master
git merge bugfix

At that stage, you can push your (now fixed) master branch to remote, and delete the bugfix branch:

git push origin master
git branch -d bugfix

Now, to integrate the latest changes on master into develop, you basically have two options.

1. Merge master into develop, by running:

   git checkout develop
   git merge master
   

   

2. Alternatively, rebase develop on top of master, by running:

   git checkout develop
   git rebase master
   

   

In either case, your develop branch will now contain the fix, and you can resume work on develop.