mendeley 0.3.2 requires requests==2.5.1, but you'll have requests 2.7.0 which is incompatible.

[yuuyins]

Description

Trying to install Parsifal on a Nix environment, I get

ERROR: pip's legacy dependency resolver does not consider dependency conflicts when selecting packages. This behaviour is the source of the following dependency conflicts.
mendeley 0.3.2 requires requests==2.5.1, but you'll have requests 2.7.0 which is incompatible.

Reproduce

1. Install Nix
2. Get https://github.com/vitorfs/parsifal/commit/ec84153e744b8f025e39a3ccdae3fdb9e70bf409
3. Go to directory parsifal

4. Create file shell.nix

   let
     pkgs = import <nixpkgs> {};
     name = "pip-env";
     venvDir = "./.venv";
   in with pkgs; mkShell rec {
     inherit name venvDir;
   
     buildInputs = [
       python27
       python27Packages.pip
       python27Packages.setuptools
       python27Packages.virtualenv # Needed when using python 2.7
       python27Packages.wheel
       postgresql_9_6
     ];
   
     # This is very close to how venvShellHook is implemented, but
     # adapted to use 'virtualenv'
     shellHook = ''
       SOURCE_DATE_EPOCH=$(date +%s)
   
       if [ -d "${venvDir}" ]; then
         printf "%s\n" "Skipping venv creation, '${venvDir}' already exists"
       else
         printf "%s\n" "Creating new venv environment in path: '${venvDir}'"
         # Note that the module venv was only introduced in python 3, so for 2.7
         # this needs to be replaced with a call to virtualenv
         ${python27Packages.virtualenv}/bin/virtualenv "${venvDir}"
       fi
   
       # Under some circumstances it might be necessary to add your virtual
       # environment to PYTHONPATH, which you can do here too;
       PYTHONPATH=$PWD/${venvDir}/${python27Packages.python.sitePackages}/:$PYTHONPATH
   
       source "${venvDir}/bin/activate"
   
       # As in the previous example, this is optional.
       pip install -r requirements.txt
     '';
   }

5. Run nix-shell --pure --show-trace shell.nix

[vitorfs]

Thanks for reporting this issue! I'm closing it now because the project is no longer using Mendeley