title: Error when installing nltk packages on heroku
body: <p>I am trying to install nltk packages in heroku using nltk.txt file. int my nltk.txt file only punkt is written. In requirements.txt file nltk is written.
  but when push it it shows the errors.
  Please help to fix my problem</p>
  
  <pre><code>remote: -----&gt; Python app detected
  remote:  !     Python has released a security update! Please consider upgrading to python-3.6.7
  remote:        Learn More: https://devcenter.heroku.com/articles/python-runtimes
  remote: -----&gt; Installing requirements with pip
  remote:
  remote: -----&gt; Downloading NLTK corpora…
  remote: -----&gt; Downloading NLTK packages: tokenize
  remote: /app/.heroku/python/lib/python3.6/runpy.py:125: RuntimeWarning: 'nltk.downloader' found in sys.modules after import of package 'nltk', but prior to execution of 'nltk.downloader'; this may result in unpredictable behaviour
  remote:   warn(RuntimeWarning(msg))
  remote: Traceback (most recent call last):
  remote:        [nltk_data] Error loading tokenize : Package 'tokenize ' not found in
  remote:   File "/app/.heroku/python/lib/python3.6/runpy.py", line 193, in _run_module_as_main
  remote:        [nltk_data]     index
  remote:     "__main__", mod_spec)
  remote:   File "/app/.heroku/python/lib/python3.6/runpy.py", line 85, in _run_code
  remote:     exec(code, run_globals)
  remote:   File "/app/.heroku/python/lib/python3.6/site-packages/nltk/downloader.py", line 2272, in &lt;module&gt;
  remote:        Error installing package. Retry? [n/y/e]
  remote:     halt_on_error=options.halt_on_error)
  remote:   File "/app/.heroku/python/lib/python3.6/site-packages/nltk/downloader.py", line 681, in download
  remote:     choice = input().strip()
  remote: EOFError: EOF when reading a line
  remote: -----&gt; Running post-compile hook
  remote: -----&gt; Running install_nltk_data
  remote: -----&gt; Starting nltk data installation
  remote: /app/.heroku/python/lib/python3.6/runpy.py:125: RuntimeWarning: 'nltk.downloader' found in sys.modules after import of package 'nltk', but prior to execution of 'nltk.downloader'; this may result in unpredictable behaviour
  remote:   warn(RuntimeWarning(msg))
  remote: [nltk_data] Downloading package punkt to /app/nltk_data...
  remote: [nltk_data]   Unzipping tokenizers/punkt.zip.
  remote: bin/install_nltk_data: line 21: cd: '/app/nltk_data': No such file or directory
  remote: -----&gt; Finished nltk data installation
  remote: -----&gt; Post-compile done
  remote: -----&gt; Discovering process types
  remote:        Procfile declares types -&gt; web
  remote:
  remote: -----&gt; Compressing...
  remote:        Done: 49M
  remote: -----&gt; Launching...
  remote:        Released v19
  remote:        https://mysterious-coast-63128.herokuapp.com/ deployed to Heroku
  remote:
  remote: Verifying deploy... done.
  To https://git.heroku.com/mysterious-coast-63128.git
     7b1a415..9b14971  master -
  </code></pre>