Move all uncommitted changes to a new branch and revert the existing branch to HEAD."master" has uncommitted changes. You decided you'd rather make those changes in "dev_branch". Here's how to move those uncommitted changes to "dev_branch" and then revert "master" to its last commit.

sync-master-to-branch.sh

#### with new branch
# get into the master branch
git checkout master

# create a new branch for the changes and check it out
git checkout -b dev_branch

# stash the changes until we revert master
git stash

# go back to master
git checkout master

# reset to the last commit
git reset --hard HEAD

# go back to dev_branch
git checkout dev_branch

# re-apply the stashed changes and you are good to go
git stash apply

#### sync existing branch with master
# verify you are in correct branch
git branch

# stash local changes 
git stash

# get into master branch
git checkout master

# get latest code from master
git fetch -p origin

# merge local master branch code with remote master
git merge origin/master

# get into your dev_branch
git checkout dev_branch

# merge local master code to local dev_branch
git merge master

# push local dev_branch changes to remote branch
git push origin dev_branch

# get the stashed changes
git stash pop