Support missing packages keyword in Client.get_versions
Previously users would get a non-informative error if their scheduler
was too old to support the packages= keyword.  Now we try again without
the keyword.  This is unfortunate because it drops the packages=
keyword, but is good because it will give a more informative error.
@@ -3180,6 +3180,8 @@ class Client(Node):
packages=packages)
except KeyError:
scheduler = None
+ except TypeError: # packages keyword not supported
+ scheduler = sync(self.loop, self.scheduler.versions) # this raises
workers = sync(self.loop, self.scheduler.broadcast,
msg={'op': 'versions', 'packages': packages})
