As reported in 974f11cb29 (commitcomment-38735081),
the tarball will fail to evaluate when updateScript is given a non-existing attrPath because getAttrFromPath
uses abort, which terminates the evaluation.
On stable releases, we will want to change the freeze parameter in pkgs/desktops/gnome-3/update.nix
to true to limit the gnome update script to only bump patch versions.
To make updating large attribute sets faster, the update scripts
are now run in parallel.
Please note the following changes in semantics:
- The string passed to updateScript needs to be a path to an executable file.
- The updateScript can also be a list: the tail elements will then be passed
to the head as command line arguments.
