meta-zephyr is another layer in OE layeridex that needed updating to work with layerindex-fetch, as it is a ”container” layer, that only points to the container, rather than the layers in the container, i.e. meta-zephyr.core and meta-zephyr-bsp, and these to layers is added to the zepto layerindex, and a layer dependancy chain was setup. As the upstream meta-zephyr git repo already have correct Yocto release branches, the zepto initiative git hosts a git mirror of it even if this is not strictly necessary.
Inspiring Best Practices in Yocto and OE Ecosystem