negative of relativedelta with weekday inconsistent

[cancan101]

For years this is consistent:

In [4]: relativedelta(years=10) == relativedelta(years=-10)
Out[4]: False

In [5]: -relativedelta(years=10) == relativedelta(years=-10)
Out[5]: True

However for weekday:
In [9]: relativedelta(weekday=1) == relativedelta(weekday=1)
Out[9]: True

In [10]: relativedelta(weekday=1) == relativedelta(weekday=-1)
Out[10]: False

In [11]: -relativedelta(weekday=1) == relativedelta(weekday=-1)
Out[11]: False