RFC 2616 states:
A client MUST be prepared to accept one or more 1xx status responses
prior to a regular response, even if the client does not expect a 100
(Continue) status message. Unexpected 1xx status responses MAY be
ignored by a user agent.
In the rare cases that we encounter a formula URL with a server that
provides a preliminary 1xx status code, it seems that (at least during
audit) we are failing on encountering this status code, even though
retrieving the file will succeed without issues.
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