- Setting values now tries to preserve the existing order, rather than
just appending to the end.
- __repr__ now returns a repr of the tuple list. The old repr becomes a
.format() method. This is clearer, makes troubleshooting easier, and
doesn't assume all data in ODicts are header-like
Make a tough call: we won't support old-style comma-separated set-cookie
headers. Real world testing has shown that the latest rfc (6265) is
often violated in ways that make the parsing problem indeterminate.
Since this is much more common than the old style deprecated set-cookie
variant, we focus on the most useful case.
