Log Message:
py-attrs: updated to 18.1.0

18.1.0:
- x=X(); x.cycle = x; repr(x) will no longer raise a RecursionError, and will \ 
instead show as X(x=...).
- attr.ib(factory=f) is now syntactic sugar for the common case of \ 
attr.ib(default=attr.Factory(f)).
- Added attr.field_dict() to return an ordered dictionary of attrs attributes \ 
for a class, whose keys are the attribute names.
- The order of attributes that are passed into attr.make_class() or the these \ 
argument of @attr.s() is now retained if the dictionary is ordered (i.e. dict on \ 
Python 3.6 and later, collections.OrderedDict otherwise).
  Before, the order was always determined by the order in which the attributes \ 
have been defined which may not be desirable when creating classes \ 
programatically.
- In slotted classes, __getstate__ and __setstate__ now ignore the __weakref__ \ 
attribute.
- Setting the cell type is now completely best effort.
  This fixes attrs on Jython.
  We cannot make any guarantees regarding Jython though, because our test suite \ 
cannot run due to dependency incompatabilities.
- If attr.s is passed a *these* argument, it will not attempt to remove \ 
attributes with the same name from the class body anymore.
- The hash of attr.NOTHING is now vegan and faster on 32bit Python builds.
- The overhead of instantiating frozen dict classes is virtually eliminated.
- Generated __init__ methods now have an __annotations__ attribute derived from \ 
the types of the fields.
- We have restructured the documentation a bit to account for attrs' growth in scope.