title: ResolvePackageNotFound error in anaconda enviroment.yml even when package requirements are satisfied?
body: <p>Am trying to follow the steps for <a href="https://github.com/HPrinz/sketch-recognition" rel="nofollow noreferrer">this (Sketch Recognition)</a>. I have to run the command <code>conda env create -f anaconda/environment.yml</code>. I installed anaconda specifically for this command but I am getting this error </p>
  
  <pre><code>(base) [duke@void paper-implementation]$ conda env create -f anaconda/environment.yml
  Collecting package metadata (repodata.json): done
  Solving environment: failed
  
  ResolvePackageNotFound: 
    - freetype==2.8=h12048fb_1
    - readline==7.0=hc1231fa_4
    - pip==9.0.1=py35h33ce766_4
    - libffi==3.2.1=h475c297_4
    - python==3.5.4=he720263_23
    - wheel==0.30.0=py35h5c0b906_1
    - numpy==1.14.0=py35h8a80b8c_1
    - libedit==3.1=hb4e282d_0
    - sqlite==3.22.0=h3efe00b_0
    - hdf5==1.8.18=h017327d_1
    - openssl==1.0.2n=hdbc3d79_0
    - tbb==4.3_20141023=0
    - mkl==2018.0.1=hfbd8650_4
    - libgfortran==3.0.1=h93005f0_2
    - libcxxabi==4.0.1=hebd6815_0
    - ca-certificates==2017.08.26=ha1e5d58_0
    - pillow==5.0.0=py35hfcce615_0
    - scipy==1.0.0=py35h8b35106_0
    - tk==8.6.7=h35a86e2_3
    - jpeg==9b=he5867d9_2
    - xz==5.2.3=h0278029_2
    - zlib==1.2.11=hf3cbc9b_2
    - libcxx==4.0.1=h579ed51_0
    - intel-openmp==2018.0.0=h8158457_8
    - libtiff==4.0.9=h0dac147_0
    - matplotlib==2.0.2=py35ha43f773_1
    - scikit-learn==0.19.1=py35h2b554eb_0
    - ncurses==6.0=hd04f020_2
  
  (base) [duke@void paper-implementation]$ pip3 install scikit-learn ncurses
  Requirement already satisfied: scikit-learn in /usr/lib/python3.6/site-packages (0.20.2)
  Collecting ncurses
    Could not find a version that satisfies the requirement ncurses (from versions: )
  No matching distribution found for ncurses
  (base) [duke@void paper-implementation]$ pip3 install scikit-learn 
  Requirement already satisfied: scikit-learn in /usr/lib/python3.6/site-packages (0.20.2)
  </code></pre>
  
  <p>Am using Linux.</p>