git sync branch from master

git checkout master
git pull
git checkout mybranch
git merge master


# to keep mybranch in sync with master

# then when you're ready to put mobiledevicesupport into master, first merge in master like above, then ...

git checkout master
git merge mybranch
git push origin master
git checkout test-branch 	//Checkout the branch you want to update
git merge master			//Merge all code from master to test-branch

// When your are done with test-branch you can merge all code into master branch
git checkout master 		// Make sure you are on master branch
git merge test-branch