title: conda env fails to create new environment
body: <p>When trying to create a new environment of the tool viper, I get stuck while solving package specifications. </p>
  
  <p>I have downloaded the tool from their <a href="https://bitbucket.org/cfce/viper/src/master/" rel="noreferrer">website</a> and unpacked it. Following the instructions I'm trying to create a conda environment named viper. </p>
  
  <p>Using the command </p>
  
  <pre><code>conda env create -f environment.yml -n viper
  </code></pre>
  
  <p>the process got stuck as mentioned above. 
  So I tried </p>
  
  <pre><code>conda create --file environment.yml -n viper
  </code></pre>
  
  <p>but I get the error</p>
  
  <pre><code>CondaValueError: could not parse 'name: viper' in: environment.yml
  </code></pre>
  
  <p>the header of my environment.yml file is attached below</p>
  
  <pre><code> name: viper
   channels: #!!python/tuple
       - bioconda
       - conda-forge
       - defaults
   dependencies:
       - ...
  </code></pre>
  
  <p>What do I do wrong? </p>
  
  <p>THe conda version I have is as such:</p>
  
  <pre><code> $ conda info
   Current conda install:
  
             platform : linux-64
        conda version : 4.3.30
     conda is private : False
    conda-env version : 4.3.30
  conda-build version : not installed
       python version : 3.6.3.final.0
     requests version : 2.18.4
     root environment : /home/yeroslaviz/miniconda3  (writable)
  default environment : /home/yeroslaviz/miniconda3
     envs directories : /home/yeroslaviz/miniconda3/envs
                        /home/yeroslaviz/.conda/envs
        package cache : /home/yeroslaviz/miniconda3/pkgs
                        /home/yeroslaviz/.conda/pkgs
         channel URLs : https://repo.continuum.io/pkgs/main/linux-64
                        https://repo.continuum.io/pkgs/main/noarch
                        https://repo.continuum.io/pkgs/free/linux-64
                        https://repo.continuum.io/pkgs/free/noarch
                        https://repo.continuum.io/pkgs/r/linux-64
                        https://repo.continuum.io/pkgs/r/noarch
                        https://repo.continuum.io/pkgs/pro/linux-64
                        https://repo.continuum.io/pkgs/pro/noarch
          config file : None
           netrc file : None
         offline mode : False
           user-agent : conda/4.3.30 requests/2.18.4 CPython/3.6.3 Linux/4.4.0-72-generic debian/stretch/sid glibc/2.23    
              UID:GID : 1000:1000
  </code></pre>
  
  <p>thanks</p>