RateLimitExceededException not raised when rate limit exceeds via making many PRs

When the rate limit is exceeded using by making too many PRs, the RateLimitExceededException is not raised, instead it is a GithubException. I would expect that it would be the rate limit exception, given it's a 403 and gives the rate limit exceeded exception:

403 {"documentation_url": "https://docs.github.com/en/free-pro-team@latest/rest/overview/resources-in-the-rest-api#secondary-rate-limits", "message": "You have exceeded a secondary rate limit. Please wait a few minutes before you try again."}

Example code:

def create_branch(repo, branch_name):
    sb = repo.get_branch(repo.default_branch)
    repo.create_git_ref(ref='refs/heads/' + branch_name, sha=sb.commit.sha)

def exceed():
    for i in range(100):
        repo = g.get_repo("mhoeger/test")
        branch = f"mhoeger/test-branch-{time.time()}"
        create_branch(repo, branch)
        repo.create_file("test.txt", "TEST!", "hi", branch)
        repo.create_pull("testing", "test", repo.default_branch, branch)

Start by reproducing the secondary-rate-limit response with the example that creates branches, files, and pull requests repeatedly. Trace how the GitHub API client handles this 403 response and compare it with RateLimitExceededException handling. Done means the documented secondary-rate-limit response raises RateLimitExceededException rather than GithubException, with tests covering the behavior.