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**Minor Improvements** (Backwards compatible)
- The `verify` keyword argument now supports being passed a path to a
directory of CA certificates, not just a single-file bundle.
- Warnings are now emitted when sending files opened in text mode.
- Added the 511 Network Authentication Required status code to the
status code registry.
**Bugfixes**
- For file-like objects that are not sought to the very beginning, we
now send the content length for the number of bytes we will actually
read, rather than the total size of the file, allowing partial file
uploads.
- When uploading file-like objects, if they are empty or have no
obvious content length we set `Transfer-Encoding: chunked` rather
than `Content-Length: 0`.
- We correctly receive the response in buffered mode when uploading
chunked bodies.
- We now handle being passed a query string as a bytestring on Python
3, by decoding it as UTF-8.
- Sessions are now closed in all cases (exceptional and not) when
using the functional API rather than leaking and waiting for the
garbage collector to clean them up.
- Correctly handle digest auth headers with a malformed `qop`
directive that contains no token, by treating it the same as if no
`qop` directive was provided at all.
- Minor performance improvements when removing specific cookies by
name.
**Miscellaneous**
- Updated urllib3 to 1.13.