title: boto3: file content length is right but the body is empty
body: <p>I have a file of size 4.4MB in an S3 bucket and when I try to download it through boto3, the content length I see in the object description is right but the body of the object is empty. Any ideas why that is happening?</p>
  
  <pre><code>s3 = session.client('s3')    
  obj = s3.get_object(Bucket=bucket, Key=key)
  obj['ResponseMetadata']['HTTPHeaders']['content-length'] ## this returns 4598667
  obj['ContentLength'] ## this returns 4598667 as well
  obj['Body'].read().decode('utf-8') ## this returns ''
  </code></pre>