text: Title: s3boto I/O operation on closed file
  Body: This i have seen a very old issue in boto and i think the issue has been solved in codes but I am geeting the "I/O operation on closed file" error whenever I'm updating images in my django site. A new image is uploaded to s3 without any problem but the error occurs when i update existing images. The images are uploaded from a frontend form.
  
  ```
  Request Method: | POST
  -- | --
  https://nakulsharma.in/dashboard/home/
  3.0.3
  ValueError
  I/O operation on closed file.
  /home2/nakulsha/virtualenv/portfolio_folder/3.7/lib/python3.7/site-packages/storages/backends/s3boto3.py in _save, line 546
  /home2/nakulsha/virtualenv/portfolio_folder/3.7/bin/python3.7
  3.7.3
  ['',  '/opt/alt/python37/bin',  '/home2/nakulsha/portfolio_folder',  '/home2/nakulsha/virtualenv/portfolio_folder/3.7/lib64/python37.zip',  '/home2/nakulsha/virtualenv/portfolio_folder/3.7/lib64/python3.7',  '/home2/nakulsha/virtualenv/portfolio_folder/3.7/lib64/python3.7/lib-dynload',  '/opt/alt/python37/lib64/python3.7',  '/opt/alt/python37/lib/python3.7',  '/home2/nakulsha/virtualenv/portfolio_folder/3.7/lib/python3.7/site-packages']
  Thu, 9 Apr 2020 11:37:35 +0000
  ```
  Any help??