Revert sorting of symbolic tags

[matthiasdiener]

Sorting fails when symbolic tags contain bare classes (which can not be compared most of the time).

The attached test case fails without this PR.

This (partially) reverts #462 until we have a better solution (like #467 or #469).

Also, TIL:

class FooTag1:
    pass

class FooTag2:
    pass

>>> FooTag1 < FooTag1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: '<' not supported between instances of 'type' and 'type'

>>> FooTag1 < FooTag2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: '<' not supported between instances of 'type' and 'type'

>>> (FooTag1,) < (FooTag1,)
False # 🤔 

>>> (FooTag1,) < (FooTag2,)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: '<' not supported between instances of 'type' and 'type'

Please squash.