title: Dirty database version error when using golang-migrate
body: <p>I am a new user of <a href="https://github.com/golang-migrate/" rel="noreferrer">golang-migrate</a>.</p>
  
  <p>I have run some migrations that executed with success.</p>
  
  <p>I am on development mode so I want to fore re-run the migrations so in <code>psql</code> shell and after connecting to my database, I executed <code>drop database schema_migrations</code></p>
  
  <p>The problem now is that when I run the code that executes the migrations (shown below)</p>
  
  <pre class="lang-golang prettyprint-override"><code>
  func RunMigrations() {
      m, err := migrate.New(
          "file://db/migrations",
          "postgres://postgres:postgres@localhost:5432/mydatabase?sslmode=disable")
      if err != nil {
          log.Fatal(err)
      }
      if err := m.Up(); err != nil {
          if err.Error() == "no change" {
              log.Println("no change made by migration scripts")
          } else {
              log.Fatal(err)
          }
      }
  }
  </code></pre>
  
  <p>I get this error</p>
  
  <blockquote>
    <p>Dirty database version 2. Fix and force version.</p>
  </blockquote>
  
  <p>What is this error about and how can I address this?</p>