title: Making a branch equal to another branch
body: <p>I have two git branches, branch_a and branch_b, both diverged from branch master.</p>
  
  <p>I have pushed branch_a. However, I want to reset all changes on branch_a and swap them for the changes on branch_b.</p>
  
  <p>I can revert branch_a to the diverging point with reversion commits, and then merge branch_b, or rebase branch_a in branch_b. Is there a simpler way? Is there any way to say: "Create a commit that make the files in branch_a become exactly equal to branch_b"? I don't want to fix conflicts. branch_a is wrong, branch_b is right. But I cannot reset to branch_b, since I have already pushed branch_a. </p>