RuntimeError: You cannot define both `content_type` and `headers[Content-Type]`.

[nschloe]

Describe the bug

In my pytests, I record responses with the fixture

import hashlib

import pytest
import responses
from responses._recorder import recorder


@pytest.fixture
def mock_requests(request):
    fname = hashlib.sha256(request.node.nodeid.encode()).hexdigest()[:16]
    yml_path = request.path.parent / "responses" / f"{fname}.yml"

    if request.config.getoption("--update-responses"):
        yml_path.parent.mkdir(exist_ok=True)
        if yml_path.exists():
            yml_path.unlink()
        with recorder as r:
            yield r
            # The register might in fact be empty, but never mind
            recorder.dump_to_file(
                file_path=yml_path,
                registered=r.get_registry().registered,
            )
    else:
        assert yml_path.exists()
        with responses.RequestsMock() as r:
            r._add_from_file(file_path=yml_path)  # noqa: SLF001
            yield r

This usually works fine, but I sometimes get responses like

responses:
  - response:
      auto_calculate_content_length: false
      body:
        '{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,4,5]],"date-time":"2025-04-05T15:23:57Z","timestamp":1743866637814},"edition-number":"1","reference-count":0,"publisher":"Wiley","isbn-type":[{"value":"9780471967583","type":"print"},{"value":"9780470868270","type":"electronic"}],"license":[{"start":{"date-parts":[[2003,6,6]],"date-time":"2003-06-06T00:00:00Z","timestamp":1054857600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2003,6,6]]},"DOI":"10.1002\/0470868279","type":"monograph","created":{"date-parts":[[2005,1,28]],"date-time":"2005-01-28T19:00:13Z","timestamp":1106938813000},"source":"Crossref","is-referenced-by-count":547,"title":["Numerical
        Methods for Ordinary Differential Equations"],"prefix":"10.1002","author":[{"given":"J.C.","family":"Butcher","sequence":"first","affiliation":[]}],"member":"311","published-online":{"date-parts":[[2005,1,28]]},"container-title":[],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/0470868279","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/0470868279","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,8,20]],"date-time":"2023-08-20T18:49:32Z","timestamp":1692557372000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/book\/10.1002\/0470868279"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2003,6,6]]},"ISBN":["9780471967583","9780470868270"],"references-count":0,"alternative-id":["10.1002\/0470868279"],"URL":"https:\/\/doi.org\/10.1002\/0470868279","relation":{},"subject":[],"published":{"date-parts":[[2003,6,6]]}}}'
      content_type: text/plain
      headers:
        access-control-allow-headers:
          X-Requested-With, Accept, Accept-Encoding, Accept-Charset,
          Accept-Language, Accept-Ranges, Cache-Control
        access-control-allow-origin: "*"
        access-control-expose-headers: Link
        connection: close
        content-encoding: gzip
        content-length: "871"
        content-type: application/json
        date: Tue, 08 Apr 2025 12:35:37 GMT
        permissions-policy: interest-cohort=()
        server: Jetty(9.4.40.v20210413)
        set-cookie:
          AWSALB=q+h9ABpvNWjFxcvQm3RXWezoK9cDzdpQ744+UzK8XrW4K/QpNE49u2geK33JiVSCotsja9oBo0d4Eq9EWYfPAlFVfltotJjVtr9Ws/ytgxvmlycVk1/rSWOT+aiz;
          Expires=Tue, 15 Apr 2025 12:35:37 GMT; Path=/, AWSALBCORS=q+h9ABpvNWjFxcvQm3RXWezoK9cDzdpQ744+UzK8XrW4K/QpNE49u2geK33JiVSCotsja9oBo0d4Eq9EWYfPAlFVfltotJjVtr9Ws/ytgxvmlycVk1/rSWOT+aiz;
          Expires=Tue, 15 Apr 2025 12:35:37 GMT; Path=/; SameSite=None
        vary: Accept-Encoding
        x-api-pool: polite
        x-rate-limit-interval: 1s
        x-rate-limit-limit: "50"
        x-ratelimit-interval: 1s
        x-ratelimit-limit: "50"
      method: GET
      status: 200
      url: https://api.crossref.org/works/10.1002%2F0470868279

When replaying, this leads to the error

E               RuntimeError: You cannot define both `content_type` and `headers[Content-Type]`. Using the `content_type` kwarg is recommended.

There is no content_type specification in my own code.

Additional context

No response

Version of responses

0.25.7

Steps to Reproduce

See above.

Expected Result

See above.

Actual Result

See above.

[beliaev-maksim]

related to #675