Requests

-------------------

**Bugfixes**

- Fixed regression from v2.12.1 for URLs with schemes that begin with
"http". These URLs have historically been processed as though they
were HTTP-schemed URLs, and so have had parameters added. This was
removed in v2.12.2 in an overzealous attempt to resolve problems
with IDNA-encoding those URLs. This change was reverted: the other
fixes for IDNA-encoding have been judged to be sufficient to return
to the behaviour Requests had before v2.12.0.

-------------------

**Bugfixes**

- Fixed several issues with IDNA-encoding URLs that are technically
invalid but which are widely accepted. Requests will now attempt to
IDNA-encode a URL if it can but, if it fails, and the host contains
only ASCII characters, it will be passed through optimistically.
This will allow users to opt-in to using IDNA2003 themselves if they
want to, and will also allow technically invalid but still common
hostnames.
- Fixed an issue where URLs with leading whitespace would raise
`InvalidSchema` errors.
- Fixed an issue where some URLs without the HTTP or HTTPS schemes
would still have HTTP URL preparation applied to them.
- Fixed an issue where Unicode strings could not be used in basic
auth.
- Fixed an issue encountered by some Requests plugins where
constructing a Response object would cause `Response.content` to
raise an `AttributeError`.

-------------------

**Bugfixes**

- Updated setuptools 'security' extra for the new PyOpenSSL backend in
urllib3.

**Miscellaneous**

- Updated bundled urllib3 to 1.19.1.

-------------------

**Improvements**

- Updated support for internationalized domain names from IDNA2003 to
IDNA2008. This updated support is required for several forms of IDNs
and is mandatory for .de domains.
- Much improved heuristics for guessing content lengths: Requests will
no longer read an entire `StringIO` into memory.
- Much improved logic for recalculating `Content-Length` headers for
`PreparedRequest` objects.
- Improved tolerance for file-like objects that have no `tell` method
but do have a `seek` method.
- Anything that is a subclass of `Mapping` is now treated like a
dictionary by the `data=` keyword argument.
- Requests now tolerates empty passwords in proxy credentials, rather
than stripping the credentials.
- If a request is made with a file-like object as the body and that
request is redirected with a 307 or 308 status code, Requests will
now attempt to rewind the body object so it can be replayed.

**Bugfixes**

- When calling `response.close`, the call to `close` will be
propagated through to non-urllib3 backends.
- Fixed issue where the `ALL_PROXY` environment variable would be
preferred over scheme-specific variables like `HTTP_PROXY`.
- Fixed issue where non-UTF8 reason phrases got severely mangled by
falling back to decoding using ISO 8859-1 instead.
- Fixed a bug where Requests would not correctly correlate cookies set
when using custom Host headers if those Host headers did not use the
native string type for the platform.

**Miscellaneous**

- Updated bundled urllib3 to 1.19.
- Updated bundled certifi certs to 2016.09.26.

-------------------

**Bugfixes**

- Fixed a bug when using `iter_content` with `decode_unicode=True` for
streamed bodies would raise `AttributeError`. This bug was
introduced in 2.11.
- Strip Content-Type and Transfer-Encoding headers from the header
block when following a redirect that transforms the verb from
POST/PUT to GET.

-------------------

**Improvements**

- Added support for the `ALL_PROXY` environment variable.
- Reject header values that contain leading whitespace or newline
characters to reduce risk of header smuggling.

**Bugfixes**

- Fixed occasional `TypeError` when attempting to decode a JSON
response that occurred in an error case. Now correctly returns a
`ValueError`.
- Requests would incorrectly ignore a non-CIDR IP address in the
`NO_PROXY` environment variables: Requests now treats it as a
specific IP.
- Fixed a bug when sending JSON data that could cause us to encounter
obscure OpenSSL errors in certain network conditions (yes, really).
- Added type checks to ensure that `iter_content` only accepts
integers and `None` for chunk sizes.
- Fixed issue where responses whose body had not been fully consumed
would have the underlying connection closed but not returned to the
connection pool, which could cause Requests to hang in situations
where the `HTTPAdapter` had been configured to use a blocking
connection pool.

**Miscellaneous**

- Updated bundled urllib3 to 1.16.
- Some previous releases accidentally accepted non-strings as
acceptable header values. This release does not.