QueryDict.copy().encoding is not set correctly

[adammck]

When QueryDict.copy() is called, a new (mutable) querydict is returned, but its 'encoding' attr is not set. This results in the copy being re-encoded wrongly. For example, this works correctly:

>>> q = QueryDict('foo=bar', encoding='rot_13')
>>> q.encoding, q.urlencode()
('foo=bar', 'rot_13')

But this is clearly wrong:

>>> q = QueryDict('foo=bar', encoding='rot_13').copy()
>>> q.encoding, q.urlencode()
('sbb=one', 'utf-8')

Oops! Patch attached, and regression tests which better illustrate the problem.

[adammck]

What needs improvement? It appears to be a pretty isolated problem with a simple fix.

[Alex Gaynor]

Bah, I didn't notice that there were 2 patches, one with tests and the other with a patch. Can you combine those into a single diff.

[Jacob]

(In [13314]) Fixed #13572: copies of QueryDicts now have their encoding set correctly.