I have tested with several packages and develop mode would
systematically trigger.

these paths will be fetched (0.02 MiB download, 0.16 MiB unpacked):
/nix/store/j7bms8a3r2pxl31x7nq9hzjzxzkfkwfk-source
copying path '/nix/store/j7bms8a3r2pxl31x7nq9hzjzxzkfkwfk-source' from 'https://cache.nixos.org'...
Sourcing python-catch-conflicts-hook.sh
Sourcing python-remove-bin-bytecode-hook.sh
Sourcing setuptools-build-hook
Using setuptoolsBuildPhase
Using setuptoolsShellHook
Sourcing pip-install-hook
Using pipInstallPhase
Sourcing python-imports-check-hook.sh
Using pythonImportsCheckPhase
Sourcing setuptools-check-hook
Using setuptoolsCheckPhase
Executing setuptoolsShellHook

Usage:
/nix/store/k0igqpz995nmxwf6piyd5jjpcc7gcnyc-python3-3.7.4/bin/python3.7 -m pip [options]

no such option: -e
Finished executing setuptoolsShellHook

There doesn't seem to be a need for eval in the setuptools-build-hook, especially as
other hooks don't have it.

Motivation for this change

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @FRidh