Installing examples and data while using existing data?

[jbednar]

Is there an easy way to install the examples and data while not forcing re-downloading of the data I already have? Datashader has huge example data files that I don't want to download again every time I install a new version, so before runnning datashader examples I created datashader-examples and made datashader-examples/data into a symlink pointing to my existing data directory. However, when I ran datashader examples, I got:

$ datashader examples
Traceback (most recent call last):
  File "/Users/jbednar/anaconda/envs/dsdocs/bin/datashader", line 10, in <module>
    sys.exit(main())
  File "/Users/jbednar/anaconda/envs/dsdocs/lib/python3.6/site-packages/datashader/__main__.py", line 9, in main
    return pyct.cmd.substitute_main('datashader',args=args)
  File "/Users/jbednar/anaconda/envs/dsdocs/lib/python3.6/site-packages/pyct/cmd.py", line 376, in substitute_main
    args.func(args) if hasattr(args,'func') else parser.error("must supply command to run") 
  File "/Users/jbednar/anaconda/envs/dsdocs/lib/python3.6/site-packages/pyct/cmd.py", line 357, in <lambda>
    egd_parser.set_defaults(func=lambda args: examples(name, args.path, args.verbose, args.force))
  File "/Users/jbednar/anaconda/envs/dsdocs/lib/python3.6/site-packages/pyct/cmd.py", line 29, in examples
    copy_examples(name, path, verbose, force)
  File "/Users/jbednar/anaconda/envs/dsdocs/lib/python3.6/site-packages/pyct/cmd.py", line 38, in copy_examples
    raise ValueError("Path %s already exists; please move it away, choose a different path, or use force."%path)
ValueError: Path /private/tmp/datashader-examples already exists; please move it away, choose a different path, or use force.

I know some ways to work around this, but I'm trying to figure out what we expect someone who upgrades their datashader to do -- presumably there should be an easy way to ensure that they upgrade the examples too, without having to download all the same data files again?