git merge master into branch

 Let's say we have the following situation in git:

A created repository:

mkdir GitTest2
cd GitTest2
git init

Some modifications in the master take place and get committed.

echo "On Master" > file
git commit -a -m "Initial commit"

Feature1 branched off master and some work is done:

git branch feature1
git checkout feature1
echo "Feature1" > featureFile
git commit -a -m "Commit for feature1"

Meanwhile, a bug is discovered in the master-code and a hotfix-branch is established

git checkout master
git branch hotfix1
git checkout hotfix1

The bug is fixed in the hotfix branch and merged back into the master (perhaps after a pull request/code review):

echo "Bugfix" > bugfixFile
git commit -a -m "Bugfix Commit"
git checkout master
git merge --no-ff hotfix1

Development on feature1 continues:

git checkout feature1

Now my question: Say I need the hotfix in my feature branch, maybe because the bug also occurs there. How can I achieve this without duplicating the commits into my feature branch? I want to prevent to get two new commits on my feature branch which have no relation to the feature implementation. This especially seems important for me if I use Pull Requests: All these commits will also be included in the Pull Request and have to be reviewed although this has already been done (as the hotfix is already in the master).

I can not do a git merge master --ff-only: "fatal: Not possible to fast-forward, aborting.", but I am not sure if this helped me. How to merge master into branch?