Root cause of linux-lts pin failure: mkimage was using dl-cdn.alpinelinux.org
while the builder uses mirrors.hosterion.ro — different mirrors can have different
package availability at any given moment.
Now mkimage reads repositories directly from /etc/apk/repositories on the builder,
ensuring both module build and ISO package install use the same mirror.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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