Configures the `--cache-dir` parameter for the prune and check commands run after backing up. For `check`, also adds a `checkOpts` flag to enable using the cache, since that is disabled by default.
this is just a hook so its safe
without this change:
we build a python3 for buildHost twice instead of only once while the result
of the build is the same
```
nix-repl> pkgsCross.aarch64-multiplatform.python3.pythonForBuild
«derivation /nix/store/5sx1ng86lxzggi33rchvq0z16ywkg11b-python3-3.10.7.drv»
nix-repl> pkgsCross.aarch64-multiplatform.buildPackages.python3
«derivation /nix/store/c5rlaqdfymd3j5v41rh98pjcv3dx3sh7-python3-3.10.7.drv»
```
```
$ nix-diff $(getOutForDrv "/nix/store/5sx1ng86lxzggi33rchvq0z16ywkg11b-python3-3.10.7.drv") $(getOutForDrv "/nix/store/c5rlaqdfymd3j5v41rh98pjcv3dx3sh7-python3-3.10.7.drv") --environment
- /nix/store/3fkwg2pypsxhydgwb9m7f1v5pcgfns6p-python3-3.10.7:{out}
+ /nix/store/wyhbl43ycqn43d08v5fqj1j6ynf7nz73-python3-3.10.7:{out}
• The input derivation named `python-setup-hook.sh` differs
- /nix/store/slvn39rh0l53c9czaf3g6a4awcj63j5r-python-setup-hook.sh.drv:{out}
+ /nix/store/bcjff6dn4gp7pf0knnja9ax4qrll78d5-python-setup-hook.sh.drv:{out}
• The set of input source names do not match:
- cross-file.conf
• The input derivation named `stdenv-linux` differs
- /nix/store/rsxsipgabvny0mc286j3vfpgaaaixdyz-stdenv-linux.drv:{out}
+ /nix/store/46ywpk0p6r22y502gi21xxghminy9lbj-stdenv-linux.drv:{out}
• The set of input derivation names do not match:
- hook
+ acl-2.3.1
+ attr-2.5.1
+ binutils-2.39
+ binutils-wrapper-2.39
+ ed-1.18
+ expand-response-params
+ gcc-11.3.0
+ gcc-wrapper-11.3.0
+ glibc-2.35-163
+ gmp-with-cxx-stage4-6.2.1
+ libidn2-2.3.2
+ libunistring-1.0
+ linux-headers-5.19
+ pcre-8.45
+ zlib-1.2.12
• The set of input derivations named `bzip2-1.0.8` do not match
• The set of input derivations named `xz-5.2.6` do not match
• The environments do not match:
+ allowedRequisites=...
defaultNativeBuildInputs=''
...
''
• The environments do not match:
cmakeFlags=''
-DCMAKE_SYSTEM_NAME=Linux -DCMAKE_SYSTEM_PROCESSOR=aarch64 -DCMAKE_HOST_SYSTEM_NAME=Linux -DCMAKE_HOST_SYSTEM_PROCESSOR=x86_64
''
configureFlags=''
--build=x86_64-unknown-linux-gnu --host=aarch64-unknown-linux-gnu
''
mesonFlags=''
--cross-file=/nix/store/0d6bflf42rgrrxhp10visp67scqncd4g-cross-file.conf
''
stdenv=''
/nix/store/6ji09gqw12pnp3ylw3rrsd65f9vhhx89-stdenv-linux/nix/store/ykjm8yzjcwg2xpf640zh6jql5s8yimkp-stdenv-linux
''
• The environments do not match:
setupHook=''
/nix/store/x6rrxsai11kl9gq29ipv0jn455admav3-python-setup-hook.sh/nix/store/h7z4wvlf7n23ir86nngjn9rpk1ygc7di-python-setup-hook.sh
''
```
This was previously disabled because pkgs.udev (=pkgs.systemd) was not building on musl, but that is no longer the case.
This fixes the build of pkgsMusl.usbutils, which requires udev support in libusb1.
Since the Nix command used is an implementation detail of the script,
it's the script that will have to be updated if the command changes,
it's the script that should be opting into this, rather than making
the user do it globally.
Since c0972c16dc ("update-python-libraries: add missing dependency nix"),
Nix will be provided as a dependency, so we know we'll always be using
a modern version and no longer need the fallback.
