python3Packages.{pyimg4,smart-meter-texas}: fix against asn1 3.x by adding asn1_2

[Bad3r]

Description of changes

python3Packages.pyimg4 has been marked broken since ef300f4, which set broken = lib.versionAtLeast asn1.version "3". nixpkgs ships asn1 3.3.0, so the guard always fires and takes ipsw-parser and pymobiledevice3 down with it:

$ nix shell nixpkgs#python3Packages.pymobiledevice3
error: Refusing to evaluate package 'python3.14-pyimg4-0.8.8' ... because it has problems:
       - broken: This package is broken.
note: trace involved the following derivations:
       derivation 'python3.14-pymobiledevice3-7.7.0'
       derivation 'python3.14-ipsw-parser-1.5.0'

The pin is not stale metadata. With the constraint relaxed and broken dropped, 5 of 7 tests fail against asn1 3.3.0:

FAILED tests/test_im4m.py::test_im4m  - asn1.core.Error: Expecting bytes or a subclass of io.RawIOBase or BufferedI...
FAILED tests/test_im4r.py::test_read  - asn1.core.Error: Expecting bytes or a subclass of io.RawIOBase or BufferedI...
FAILED tests/test_img4.py::test_read  - pyimg4.errors.UnexpectedTagError: Expected tag of type IA5String, got Print...

python-asn1 3.0 changed Decoder.read() to recursively decode constructed elements into nested lists instead of returning their raw content octets, which is what parser.py re-parses and re-emits throughout. Upstream declined the port in m1stadev/PyIMG4#59 ("Version 3.0.0 is technically much better, but pyimg4 should be refactored around it first to support it") and has not released since v0.8.8 in April 2025.

So this adds asn1_2 at 2.8.0, the last 2.x, and builds pyimg4 against it, following the existing convention for versioned Python attributes (cython_0, chardet_5, django_5). asn1 stays at 3.3.0 as the default; pyimg4 is its only in-tree consumer (smart-meter-texas is the other, and ldap3 uses pyasn1, not asn1). No pythonRelaxDeps is needed since 2.8.0 satisfies upstream's asn1>=2.7.0,<3.0.0 directly.

I have also proposed the actual port upstream in m1stadev/PyIMG4#63. Once that lands and is released, pyimg4 can move back to asn1 and asn1_2 can go.

Verification

nix-build -A python3Packages.pyimg4           # 7 passed, 5 deselected
nix-build -A python3Packages.ipsw-parser      # ok
nix-build -A python3Packages.pymobiledevice3  # 56 passed, 113 deselected, 1 xfailed
nix-build -A python3Packages.asn1_2 -A python3Packages.asn1
nix-instantiate ./. -A python3Packages.{asn1_2,pyimg4,ipsw-parser,ldap3} \
                    -A python312Packages.pyimg4 -A python313Packages.asn1_2
nix fmt   # 0 changed

nix-store -qR on the pymobiledevice3 output contains python3.14-asn1-2.8.0 and no 3.3.0, so there is no module collision in the closure.

The affected set is closed and was built in full by hand rather than via nixpkgs-review: asn1_2 is new and only pyimg4 consumes it, pyimg4's only reverse dependency is ipsw-parser, whose only reverse dependency is pymobiledevice3, which nothing else in tree depends on. All four are built above.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in /etc/nix/nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.