I am working on a project that has two branches: master and feature
The feature branch was created some time ago and has numerous
when you do
git pull --rebase origin/upstream master
it checks if there were recent code merge by others. if that's so, you'll have to make your current work tree aligned with what's in the upstream.
you could see the changed file which you've to relook by
git status
after you resolve them,
git add
and
git commit and then
git push -f origin will make you happy.