User facing AssertionError in empty groupby GH5289
closes https://github.com/pydata/pandas/issues/5289 
Is this all we need to do?
Or am I missing something?

would be nice to have a test that hits this

also need to remove the .deb file that seemed to be added to the repo
 Ok doing that - might need  abit of help with the tests - since I'm not an expert on these yet.
 @springcoil can you revisit
 Ok I'll have a look and see what is going wrong. 
 closing pls reopen if/when updated
