[downloader:http] close connection when file already exists (#3748)

gallery_dl/downloader/http.py

@@ -225,6 +225,14 @@ def _download_impl(self, url, pathfmt):
  pathfmt.build_path()
  if pathfmt.exists():
  pathfmt.temppath = ""
+ # release the connection back to pool by explicitly
+ # calling .close()
+ # see https://requests.readthedocs.io/en/latest/user
+ # /advanced/#body-content-workflow
+ # when the image size is on the order of megabytes,
+ # re-establishing a TLS connection will typically be faster
+ # than consuming the whole response
+ response.close()
  return True
  if self.part and metadata:
  pathfmt.part_enable(self.partdir)
@@ -246,6 +254,7 @@ def _download_impl(self, url, pathfmt):
  if self._adjust_extension(pathfmt, file_header) and \
  pathfmt.exists():
  pathfmt.temppath = ""
+ response.close()
  return True
 
  # set open mode