fix: Handle Retry-After headers better for 429 responses

We have to ensure we normalize the headers before we search for the
Retry-After header.

src/rhsm/connection.py

@@ -500,10 +500,14 @@ class RateLimitExceededException(RestlibException):
  The retry_after attribute may not be included in the response.
  """
 
- def __init__(self, code: int, msg: str = None, headers: str = None) -> None:
+ def __init__(self, code: int, msg: str = None, headers: dict = None) -> None:
  super(RateLimitExceededException, self).__init__(code, msg)
  self.headers = headers or {}
- self.retry_after = safe_int(self.headers.get("retry-after"))
+ self.retry_after = None
+ for header, value in self.headers.items():
+ if header.lower() == "retry-after":
+ self.retry_after = safe_int(value)
+ break
  self.msg = msg or "Access rate limit exceeded"
  if self.retry_after is not None:
  self.msg += ", retry access after: %s seconds." % self.retry_after