Let's make Impala the best release so far! 🚗 🦌

We have: the main jobset starting around 1.5k failures, x86_64-darwin around 0.9k, and the newbie aarch64-linux lagging behind near 4k. The numbers seem large, but one package may kill very many jobs...

Steps to repeat

• Choose some package from those that fail on Hydra. Hurry before the good ones have been taken!
• Find a fix. That may mean simply restricting meta.platforms, in case the package inherently doesn't support what it has in there ATM.
• Typically the package was broken on master already. You can verify that on Hydra - example URL: https://hydra.nixos.org/job/nixpkgs/trunk/bash.x86_64-linux In that case base the fix on master and request backporting in the description of the pull request.
• Ping this issue from the PR, e.g. /cc ZHF 18.03 Zero Hydra Failures (generic + x86_64-linux) #36453. Do this also if you have some WIP. Alternatively you may just post a note in this issue. If the breakage is specific to darwin 18.03 Zero Hydra Failures - Darwin edition #36454 or aarch64 18.03 Zero Hydra Failures - aarch64 edition #32326, mention the respective issue instead.

The remaining packages will be marked as broken before the release (on the failing platforms), i.e. at the end of March. /cc @NixOS/nixpkgs-committers, but everyone can fix the stuff.