Release 2.2.1

[pquentin]

• See if all tests, including downstream, pass
• Get the release pull request approved by a CODEOWNER
• Squash merge the release pull request with message "Release <VERSION>"
• Tag with X.Y.Z, push tag on urllib3/urllib3 (not on your fork, update <REMOTE> accordingly)
  • Notice that the <VERSION> shouldn't have a v prefix (Use 1.26.6 instead of v.1.26.6)

  • # Ensure the release commit is the latest in the main branch.
    git checkout main
    git pull origin main
    git tag -s -a '<VERSION>' -m 'Release: <VERSION>'
    git push <REMOTE> --tags
    

• Execute the publish GitHub workflow. This requires a review from a maintainer.
• Ensure that all expected artifacts are added to the new GitHub release. Should
  be one .whl, one .tar.gz, and one multiple.intoto.jsonl. Update the GitHub
  release to have the content of the release's changelog.
• Announce on:
  • Twitter
  • Mastodon
  • Discord
  • OpenCollective
• Update Tidelift metadata
• If this was a 1.26.x release, add changelog to the main branch

[illia-v]

Thanks @pquentin!

[pquentin]

@illia-v mentioned that #3203 made a similar change to the one reverted in #3344, so I need to inspect it before proceeding with the release. At the very least we need to be sure that botocore will work with 2.2.1.

[nateprewitt]

Confirmed current tip of main works in botocore as expected. Looking at #3203 it's a similar change but appears to only affect the request API and test infrastructure. We aren't using either so I think it's safe to say we're unaffected. The one to request may cause similar issues for other users though.

[pquentin]

Having looked more closely at #3203, I see two ways to avoid using HTTPHeaderDict. I can ignore the type errors as done in #3344, like this:

diff --git a/src/urllib3/_request_methods.py b/src/urllib3/_request_methods.py
index 632042f0..49495c3e 100644
--- a/src/urllib3/_request_methods.py
+++ b/src/urllib3/_request_methods.py
@@ -122,8 +122,8 @@ class RequestMethods:
                 headers = self.headers
 
             if not ("content-type" in map(str.lower, headers.keys())):
-                headers = HTTPHeaderDict(headers)
-                headers["Content-Type"] = "application/json"
+                headers = headers.copy()  # type: ignore[attr-defined]
+                headers["Content-Type"] = "application/json"  # type: ignore[index]
 
             body = _json.dumps(json, separators=(",", ":"), ensure_ascii=False).encode(
                 "utf-8"

But I would like less ignores, not more. The other option, suggested in python/mypy#5970, is to accept that headers can indeed be immutable given the typing.Mapping type, which means they have to be converted to dicts before being modified:

diff --git a/src/urllib3/_request_methods.py b/src/urllib3/_request_methods.py
index 632042f0..f08b69e8 100644
--- a/src/urllib3/_request_methods.py
+++ b/src/urllib3/_request_methods.py
@@ -122,6 +122,13 @@ class RequestMethods:
                 headers = self.headers
 
             if not ("content-type" in map(str.lower, headers.keys())):
+                # While headers is most likely dict or HTTPHeaderDict, it can
+                # also be an arbitrary immutable mapping that will stay
+                # immutable even after calling copy().
+                if isinstance(headers, HTTPHeaderDict):
+                    headers = headers.copy()
+                else:
+                    headers = dict(headers)
                 headers = HTTPHeaderDict(headers)
                 headers["Content-Type"] = "application/json"

But this is more complicated code for a case that we don't care about (immutable headers object that is not dict or HTTPHeaderDict).

In summary, given that:

• the above potential "fixes: are undesirable,
• botocore works with Move test_skip_header to test/test_connection.py #3202 and the proposed release,
• HTTPHeaderDict not supporting byte values does not affect this part of the code,
• and that unlike urllib3/connectionpool.py, code in urllib3/_request_methods.py does not have proxy headers of a different type

I'd like to release 2.2.1 as is.