title: FLOAT values loaded from CSV are not parsed correctly
body: <p>I have a CSV file which I am loading to BigQuery using this schema:</p>
  
  <pre><code>[
    {"name": "l1", "type": "float", "mode": "nullable"},
    {"name": "l2", "type": "float", "mode": "nullable"},
  ]
  </code></pre>
  
  <p>My data looks like this:</p>
  
  <pre><code>40.7125,-73.8154
  34.1007,-81.227
  34.1003,-81.2273
  </code></pre>
  
  <p>After loading the data into BigQuery, it becomes like this:</p>
  
  <pre><code>40.712501525878906,-73.81539916992188
  34.10070037841797,-81.22699737548828    
  34.10029983520508,-81.22730255126953
  </code></pre>
  
  <p>How this is possible? Where all the extra digits are coming from?</p>