title: Git merge master into branch and new feature
body: <p>I have 2 components being developed at the same time component A and component B. And component A needs to use component B for it to be complete. </p>
  
  <p>If component B is completed first and then merged into master as it is a stand alone component. How should I go about getting that into A so it can be completed?</p>
  
  <p>After merging B into master should I merge master into A?</p>
  
  <p>Should I merge A in half done and then retrench? (This doesn't seem correct)</p>
  
  <p>Is there some option that I am missing?</p>
  
  <p>Thank you</p>