"Operation not permitted" errors due to race condition in clearing/setting the immutable bit #9
Description
building path(s) `/nix/store/3ap0adrzz2xz5b6my1pfwrry7j08ar9r-nixos-test-driver'
error: linking `/nix/store/2z2ff51yskqm44kddd10hv4xg2mp40lp-nixos-test-driver.drv.chroot/nix/store/c1n81qbnpp98npc6idkkk4a4z8jnzw1s-upstart-udevtrigger.conf' to `/nix/store/c1n81qbnpp98npc6idkkk4a4z8jnzw1s-upstart-udevtrigger.conf': Operation not permitted
This is due to build.cc:
makeMutable(*i);
link(i->c_str(), ...);
makeImmutable(*i);
If two processes do this at the same time, one may call makeImmutable() before the other has called link().