title: How to initiate a new columns with None and update its value with tuple conditionally?
body: <p>I have the following code</p>
  <pre><code>import pandas as pd
  d = [{'points': 50, 'time': '5:00', 'year': 2010},
       {'points': 25, 'time': '6:00', 'month': &quot;february&quot;},
       {'points': 90, 'time': '9:00', 'month': 'january'},
       {'points_h1': 20, 'month': 'june'}]
  df = pd.DataFrame(d)
  df['auditor'] = None
  df.loc[df['points'] == 50, 'auditor'] = (1, 2)
  print(df)
  print(df.loc[df['points'] == 50, 'auditor'])
  </code></pre>
  <p>I want to initiate a new column and with <code>None</code> and conditionally update its value with a <code>tuple</code> but it occurs the following error.</p>
  <pre><code>ValueError: cannot set using a multi-index selection indexer with a different length than the value
  </code></pre>
  <p>my desire result is</p>
  <pre><code>      month  points  points_h1  time  year  auditor
  0       NaN      50        NaN  5:00  2010  (1,2)
  1  february      25        NaN  6:00   NaN  None
  2   january      90        NaN  9:00   NaN  None
  3      june     NaN         20   NaN   NaN  None
  </code></pre>
  <p>how may I do so?</p>