Future repr issue in Jupyter Notebook

[jakirkham]

When trying to inspect a Future in the Jupyter Notebook, an issue cropped up trying to represent it. Looks like it assumes a key is a str when it is in fact a tuple. Running distributed version 1.20.1.

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
/opt/conda3/lib/python3.6/site-packages/IPython/core/formatters.py in __call__(self, obj)
    343             method = get_real_method(obj, self.print_method)
    344             if method is not None:
--> 345                 return method()
    346             return None
    347         else:

/opt/conda3/lib/python3.6/site-packages/distributed/client.py in _repr_html_(self)
    334                 typ = str(self.type)
    335             text += '<font color="gray">type: </font>%s, ' % typ
--> 336         text += '<font color="gray">key: </font>%s' % html_escape(self.key)
    337         return text
    338 

/opt/conda3/lib/python3.6/html/__init__.py in escape(s, quote)
     17     translated.
     18     """
---> 19     s = s.replace("&", "&amp;") # Must be done first!
     20     s = s.replace("<", "&lt;")
     21     s = s.replace(">", "&gt;")

AttributeError: 'tuple' object has no attribute 'replace'

<Future: status: finished, type: Array, key: ('store-rechunk-merge-9d56828f48fdb9af2a81e6b10a09d976', 3, 3, 0)>