It is an openwrt bug in include/prereq-build.mk:
But the link do not exist. I have git-version-check-fix.patch, but do not know, how to use it.
Which git version do you have installed in your buildhost?
Just install a current git version to your PC.
git is not part of Openwrt sources, it is an external prerequisite. Mentioned on the list here: https://wiki.openwrt.org/doc/howto/buildroot.exigence
And no idea what is "spack", and what is its relevance to Openwrt/LEDE...
Ps. the correct link to old chaos calmer sources would be
There's a patch for the issue...
~/Oolite8/openwrt15$ git --version
git version 2.16.1
Is it a current git version?
~/Oolite8/openwrt15$ git apply git-version-check-fix.patch solved the problem. Link: