title: error Migrations are pending; run 'rake db:migrate RAILS_ENV=development' to resolve this issue
body: <p>I tried to rollback the last migration :</p>
  
  <pre><code>rake db:rollback
  </code></pre>
  
  <p>it show  me the following :</p>
  
  <pre><code>==  AddUserIdToPictures: reverting ============================================
  -- remove_index(:pictures, {:column=&gt;[:user_id, :visible]})
  -&gt; 0.1201s
  -- remove_column(:pictures, :user_id, :integer)
  -&gt; 0.0127s
  ==  AddUserIdToPictures: reverted (0.1567s) ===================================
  </code></pre>
  
  <p>then if i try to access some page i get error :</p>
  
  <pre><code>Migrations are pending; run 'rake db:migrate RAILS_ENV=development' to resolve this issue
  </code></pre>
  
  <p>but when i do what error says : rake db:migrate RAILS_ENV=development , it recreate what i rollback above :</p>
  
  <pre><code>==  AddUserIdToPictures: migrating ============================================
  -- add_column(:pictures, :user_id, :integer)
  -&gt; 0.0300s
  -- add_index(:pictures, [:user_id, :visible])
  -&gt; 0.1007s
  ==  AddUserIdToPictures: migrated (0.1310s) ===================================
  </code></pre>
  
  <p>what is wrong here ? should i remove the migration file before i run the command ?</p>