title: Pandas SettingWithCopyWarning: A value is trying to be set on a copy of a slice from a DataFrame
body: <p>I keep getting the warning in the subject in the following situations:</p>
  <p>Step 1:</p>
  <pre><code>df.rename(columns={'one':'one_a'}, inplace=True)
  </code></pre>
  <p>Step 2:</p>
  <pre><code>df.drop(['one', 'two', 'three'], axis=1, inplace=True)
  </code></pre>
  <p>How do I fix?</p>