Should stop immediately when receiving an HTTP 429 (rate-limit) status

I'm looking at the result of a Wesnoth CI build, but AFAICS the files are the same in this repo.
https://github.com/wesnoth/wesnoth/actions/runs/7688512844/job/20949816292?pr=8281

```
Generate map diff image for data/campaigns/Under_the_Burning_Suns/maps/04_Descending_into_Darkness.map...
diff_image.png PNG 4804x3140 4804x3140+0+0 8-bit sRGB 21.3869MiB 0.000u 0:00.000
Compress image...
diff_image.png PNG 4804x3140 4804x3140+0+0 8-bit sRGB 256c 2.60584MiB 0.000u 0:00.000
Uploading diff_image.png...
{"errors":[{"id":"legacy-api-6d6df4d754-kt4nd/qV43zolB2Z-5258615","code":"429","status":"Too Many Requests","detail":"Too Many Requests"}]}
Generating HTML comment...
Check out data/campaigns/Under_the_Burning_Suns/maps/08_Out_of_the_Frying_Pan.map from 062400441cdfbaf62f74736e919e875ccad7fcd4...
Generate map diff image for data/campaigns/Under_the_Burning_Suns/maps/08_Out_of_the_Frying_Pan.map...
diff_image.png PNG 8692x4076 8692x4076+0+0 8-bit sRGB 39.806MiB 0.000u 0:00.000
Compress image...
diff_image.png PNG 8692x4076 8692x4076+0+0 8-bit sRGB 256c 4.18947MiB 0.000u 0:00.000
Uploading diff_image.png...
Too Many Requests{"errors":[{"id":"legacy-api-6d6df4d754-kt4nd/qV43zolB2Z-5258807","code":"429","status":"Too Many Requests","detail":"Too Many Requests"}]}
Generating HTML comment...
Check out data/test/maps/4p_separate_castles.map from 062400441cdfbaf62f74736e919e875ccad7fcd4...
Too Many Requestsfatal: path 'data/test/maps/4p_separate_castles.map' exists on disk, but not in '062400441cdfbaf62f74736e919e875ccad7fcd4'
Error: Process completed with exit code 128.
```

HTTP 429 is a rate-limit, so making more requests immediately afterwards is expected to fail, but more seriously each request is likely to be counted against the rate limit, thus making subsequent requests more likely to fail too.

Expected behavior would be to stop immediately on the first 429 response.