MultiDict.copy() doesn't work with istr keys

[alexdutton]

Here's a small test case:

>>> import multidict
>>> m=multidict.CIMultiDict({multidict.istr('Foo'): 'bar'})
>>> m.copy()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "multidict/_multidict.pyx", line 325, in multidict._multidict.MultiDict.copy (multidict/_multidict.c:6830)
  File "multidict/_multidict.pyx", line 251, in multidict._multidict.MultiDict.__init__ (multidict/_multidict.c:5495)
  File "multidict/_multidict.pyx", line 289, in multidict._multidict.MultiDict._extend (multidict/_multidict.c:6115)
TypeError: Expected str, got istr

MultiDict._extend expects every key to be a str. aiohttp.hdrscreates istr objects, so request.headers.copy() doesn't work.

[asvetlov]

Good catch!
I'll fix it in a few hours.

[asvetlov]

Fixed by c79c3a3 and released as `multidict==2.1.1"