title: rake db:migrate updating schema.rb with dropped tables
body: <p>I have several branches on git, the schema across these branches are on different versions.
  After switching to a branch lets say <code>new_feature</code>(with pending migration) if I do <code>rake db:setup</code> then it advice me to run the pending migration.</p>
  
  <p>Once I do that my schema gets updated with tables those were deleted in the same branch.</p>
  
  <p>If I do <code>rake db:reset</code> then it works fine.</p>
  
  <p>I know the difference between <code>db:setup</code> and <code>db:reset</code>.
  The later one does <code>db:drop</code> and then <code>db:setup</code></p>
  
  <p>But am wondering why the schema shows up those dropped tables on <code>rake db:migrate</code></p>
  
  <p>Am sure am missing some rails knowledge w.r.t. schema loading and migration process</p>
  
  <p>Any insights would be of great help. Thanks in advance</p>