python36Packages.rlp fails to build

[nek0]

Issue description

Above mentioned package fails to build wiith following error:

Processing ./rlp-1.0.1-py2.py3-none-any.whl
Collecting eth-utils<2,>=1.0.2 (from rlp==1.0.1)
  Could not find a version that satisfies the requirement eth-utils<2,>=1.0.2 (from rlp==1.0.1) (from versions: )
No matching distribution found for eth-utils<2,>=1.0.2 (from rlp==1.0.1)
builder for '/nix/store/259lk8n561lxni9j6vpiwpcxlhiifdv9-python3.6-rlp-1.0.1.drv' failed with exit code 1

Steps to reproduce

run nix-env -iA nixos.python36Packages.trezor

Technical details

• system: "x86_64-linux"
• host os: Linux 4.14.56, NixOS, 18.09pre146471.d7d31fea7e7 (Jellyfish)
• multi-user?: yes
• sandbox: no
• version: nix-env (Nix) 2.0.4
• channels(root): "nixos-18.09pre145679.dae9cf6106d, nixpkgs-18.09pre147646.408bd2b80ed"
• channels(nek0): ""
• nixpkgs: /root/.nix-defexpr/channels/nixpkgs

[nek0]

@np can you have a look at this?

[dotlambda]

Seems like eth-utils is not yet packaged in nixpkgs. It would be best to create a PR that adds that to nixpkgs and updates the expression for python3Packages.rlp.
Btw, last time rlp was updated to 1.0.1, it was first marked as broken in e00ddc6 by @FRidh and then reverted to 0.6.0 in 367a7ae by @Profpatsch. However, packaging the new dependency is preferable.

[dotlambda]

One dependency that also needs to be packaged is setuptools-markdown. It will however not be possible to make it work because it requires pypandoc, which is incompatible with our version of pandoc.
Therefore, I created msabramo/setuptools-markdown#19, which can be applied as a patch when packaging setuptools-markdown.

[dotlambda]

I've began packaging the new dependencies over at https://github.com/dotlambda/nixpkgs/commits/fix-rlp.
However, I have no interest in running useless calculations on my graphics card so I'm not going to continue work on this. I hope someone of @nek0 @deepfire @gebner @Profpatsch finishes this.

[Enzime]

I'm not sure if pypandoc actually does not work with pandoc>=2.

From what I can tell, it looks to me like the Arch python-pypandoc package uses pandoc>=2 however I have not tested that this package actually works: https://git.archlinux.org/svntogit/community.git/tree/trunk/PKGBUILD?h=packages/python-pypandoc

Also looking at the code for pypandoc it appears to be downloading pandoc>=2, so I'm guessing it might actually work with pandoc>=2 to some degree:

https://github.com/bebraw/pypandoc/blob/master/pypandoc/pandoc_download.py#L24-L41

This is the error I get after adding doCheck = false; and letting it build pypandoc, when other libraries attempt to actually use pypandoc.

Traceback (most recent call last):
  File "/nix/store/ylybfm2wdy4npsiryzpn1vbpv3fagyix-python3.6-setuptools-markdown-0.2/lib/python3.6/site-packages/setuptools_markdown.py", line 22, in long_description_markdown_filename
    output = pypandoc.convert(markdown_filename, 'rst')
  File "/nix/store/yzm46clpxbdyc7drcmyn9grmg2wiqpzd-python3.6-pypandoc-1.4/lib/python3.6/site-packages/pypandoc/__init__.py", line 69, in convert
    outputfile=outputfile, filters=filters)
  File "/nix/store/yzm46clpxbdyc7drcmyn9grmg2wiqpzd-python3.6-pypandoc-1.4/lib/python3.6/site-packages/pypandoc/__init__.py", line 260, in _convert_input
    _ensure_pandoc_path()
  File "/nix/store/yzm46clpxbdyc7drcmyn9grmg2wiqpzd-python3.6-pypandoc-1.4/lib/python3.6/site-packages/pypandoc/__init__.py", line 544, in _ensure_pandoc_path
    raise OSError("No pandoc was found: either install pandoc and add it\n"
OSError: No pandoc was found: either install pandoc and add it
to your PATH or or call pypandoc.download_pandoc(...) or
install pypandoc wheels with included pandoc.