title: What all the steps Liquibase follows while rolling back?
body: <p>I don't understand the detailed steps when rolling back using Liquibase.  </p>
  
  <p>I had scenario like 6 changesets and for one changeSet rollback was not defined - that is, only <code>&lt;rollback/&gt;</code> within the changeset.  </p>
  
  <p>After executing using deployIT I could see 7 entries in Databasechangelog table, 6 for added, one for tag creation due usage of deployIT.  </p>
  
  <p>After rolling back I saw the behavior of removing all newly added 6 changesets even though one of the six changesets had an empty rollback tag.</p>
  
  <p>Please any expert tell me why? What is the exact behavior of rollback?  </p>
  
  <p>Overall want to know when records from Databasechangelog removed ?</p>