From the docs:
The OrderedDict constructor and
update()method both accept keyword arguments, but their order is lost because Python’s function call semantics pass-in keyword arguments using a regular unordered dictionary.
So initialization loses the ordering, because it’s basically calling a constructor with **kwargs.
Edit: In terms of a solution (not just an explanation)—as pointed out in a comment by the OP, passing in a single list of tuples will work:
>>> from collections import OrderedDict
>>> spam = OrderedDict([('s',(1,2)),('p',(3,4)),('a',(5,6)),('m',(7,8))])
>>> for key in spam:
... print(key)
...
s
p
a
m
>>> for key in spam.keys():
... print(key)
...
s
p
a
m
This is because it’s only getting a single argument, a list.