Why did this build fail?

https://copr.fedorainfracloud.org/coprs/hazel-bunny/ports/build/6477992/

Nothing in the log seems problematic but build failed. Built rpms are in chroot, however. Spent weekends trying to figure out what went wrong, to no result.

Quick search for string error: found me this piece of log, which is not present in the logs of the successful builds:

INFO: Pulling image: registry.fedoraproject.org/fedora:rawhide
ERROR: Trying to pull registry.fedoraproject.org/fedora:rawhide...
Error: copying system image from manifest list: parsing image configuration: Get "https://cdn.registry.fedoraproject.org/v2/fedora/blobs/sha256:e96acc78cf165996289fa8c0ac8ea2955361380571b0028e4521ebeb9f9be51d": dial tcp: lookup cdn.registry.fedoraproject.org: no such host

https://download.copr.fedorainfracloud.org/results/hazel-bunny/ports/fedora-rawhide-x86_64/06477992-oomox-qt/builder-live.log.gz

So I’d start investigating there.

Usually I start such debugging by searching for err:, error: and fail keywords.