tevent: pytalloc-util not found

[gtgteq]

Describe the bug
build of tevent failed.

To Reproduce

$ nix-shell -p tevent
...
Checking for system talloc (>=2.1.13)                                                           : yes
Checking for system pytalloc-util (>=2.1.13)                                                    : not found
ERROR: System library pytalloc-util of version 2.1.13 not found, and bundling disabled
builder for '/nix/store/aryzqwvawf3s4n1f6rk93bxq9q7dpi5g-tevent-0.9.37.drv' failed with exit code 1
error: build of '/nix/store/aryzqwvawf3s4n1f6rk93bxq9q7dpi5g-tevent-0.9.37.drv' failed

Metadata

• system: "x86_64-linux"
• host os: Linux 4.19.107, NixOS, 20.09pre215183.7948e6785b4 (Nightingale)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.3
• channels(root): "nixos-20.09pre215183.7948e6785b4"
• channels(gtgteq): ""
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
# a list of nixos modules affected by the problem
module:
- services.sssd

[jtojnar]

Looks like regression in d617e54. We need to build talloc with Python 3 too.

[jtojnar]

It might also need #58380