Various broken or nonsensical behaviors with h-matchers's fluent interface

[seanh]

This would probably be better as multiple separate issues if we actually planned to fix them, but I I'm writing this more for reference because I'm thinking of deprecating h-matchers rather than fixing these issues.

>>> # This should assert that the left-hand-side contains 1, 2, 3 and 4.
>>> # In fact it does not raise even though 1, 2, and 3 are missing.
>>> assert [4] == Any.list.containing([1,2,3]).containing([4])

>>> # It makes no sense to call Any.list.only() (rather than Any.list.contains([...]).only()).
>>> # This should raise a sensible exception but raises a bizarre one.
>>> assert [] == Any.list.only()
-> TypeError: ContainsMixin.only() missing 1 required positional argument: 'self'

>>> # It's redundant to call Any.list.comprised_of(n).only() but it should just
>>> # work and be equivalent to Any.list.comprised_of(n).
>>> # Instead if gives an unclear exception.
>>> assert [1,1,1] == Any.list.comprised_of(1).only()
-> ValueError: You must set items before calling this

The fluent interface style leads to a combinatorial explosion that inevitably opens up all kinds of unforeseen combinations. I bet there’s lots more of these.