title: how to convert buffer read from sqlite3 to bitarrary
body: <p>code:</p>
  
  <pre><code>from bitarray import bitarray
  import sqlite3
  
  a  = bitarray('1001011')
  
  conn = sqlite3.connect(":memory:")
  # conn = sqlite3.connect('tmp.db')
  cursor = conn.cursor()
  
  cursor.execute("CREATE TABLE t (id INTEGER, x BLOB)")
  
  cursor.execute("INSERT INTO t values (?, ?)", (1, sqlite3.Binary(a.tobytes())))
  cursor.execute("select * from t")
  
  rec = cursor.fetchone()
  
  conn.commit()
  conn.close()
  
  b = bitarray.frombytes(rec[1])
  </code></pre>
  
  <p>error:</p>
  
  <pre><code>---------------------------------------------------------------------------
  TypeError                                 Traceback (most recent call last)
  18 conn.close()
  19
  ---&gt; 20 b = bitarray.frombytes(rec[1])
  
  TypeError: descriptor 'frombytes' requires a 'bitarray._bitarray' object but received a 'buffer'
  </code></pre>