A gateway that answers 429 with Retry-After: inf (or 1e999, which float()
happily rounds to inf) used to reach backoff_delay as retry_after_s=inf.
max(delay, retry_after) then picked it, and since the library deliberately
does not clamp the hint with backoff_max_s, the attempt slept forever.
- _parse_retry_after now rejects non-finite values via math.isinf and
returns None, so the call falls back to plain exponential backoff
- it emits exactly one warning carrying the source name and the verdict
word retry_after_not_finite, never the raw header: under a 429 storm an
echoed header drowns the real signal and does not help localisation
- source_name becomes a required keyword-only argument; the function is
private, so no default is given and a missed call site fails loudly
instead of silently dropping the source identity from the warning
- nan keeps flowing through the existing seconds > 0 semantics; no new
branch, no reordering of the parse
iomgaa
da77b123ec