pythonPackages.mysqlclient fails to build

[Gerschtli]

Issue description

In current master branch pythonPackages.mysqlclient fails to build.

Steps to reproduce

Checkout nixpkgs on revision 132a9a0 and run:

$> nix build -f . pythonPackages.mysqlclient
builder for '/nix/store/1wcp8ym36476w0h89ayqxcm936fm4xrq-python2.7-mysqlclient-1.4.2.post1.drv' failed with exit code 1; last 10 log lines:
  Traceback (most recent call last):
    File "nix_run_setup", line 8, in <module>
      exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\\r\\n', '\\n'), __file__, 'exec'))
    File "setup.py", line 16, in <module>
      metadata, options = get_config()
    File "/build/mysqlclient-1.4.2.post1/setup_posix.py", line 51, in get_config
      libs = mysql_config("libs")
    File "/build/mysqlclient-1.4.2.post1/setup_posix.py", line 29, in mysql_config
      raise EnvironmentError("%s not found" % (_mysql_config_path,))
  EnvironmentError: mysql_config not found
[0 built (1 failed), 5 copied (55.7 MiB), 10.4 MiB DL]
error: build of '/nix/store/1wcp8ym36476w0h89ayqxcm936fm4xrq-python2.7-mysqlclient-1.4.2.post1.drv' failed            

Technical details

• system: "x86_64-linux"
• host os: Linux 4.14.103, NixOS, 18.09.2327.37694c8cc0e (Jellyfish)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.1.3
• channels(root): "nixos-18.09.2327.37694c8cc0e"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

[jtojnar]

Most likely caused by enabling strictDeps . Unfortunately, the config-tools are not very configuration friendly.
Until #51176 is resolved, I would add strictDeps = false; to the package.

[Gerschtli]

Unfortunately this does not change anything, still failing with the same error message..

[jtojnar]

Hmm, apparently mkPythonDerivation just hardcodes the path without the ability to override it from the attrset passed to buildPythonPackage:

nixpkgs/pkgs/development/interpreters/python/mk-python-derivation.nix

Line 91 in c94f6f2

strictDeps = true;

Is that intentional, @FRidh?

Until this is resolved, you can use pythonPackages.mysqlclient.overrideAttrs (old: {strictDeps = false;}):

$ nix build -f . '(with import <nixpkgs> {}; pythonPackages.mysqlclient.overrideAttrs (old: {strictDeps = false;}))'