So currently you can only see what are the dependencies or the superseder of an issue, but you can't see if an issue is a dependency or a superseder of another issue unless you like in the history, for example:

http://bugs.python.org/issue6494 is superseder of http://bugs.python.org/issue7987
#7987 has #6494 in the superseder field, but #6494 only has a mention of #7987 in the history.

http://bugs.python.org/issue6484 is a dependency of http://bugs.python.org/issue9923
#9923 has #6484 in the dependencies field, but #6484 only has a mention of #9923 in the history.

The info that is now available only in the history could be moved in the dependencies/superseder field (with a label that says "dependency of/superseder of"), or in a new field visible only when the value is present (but that would leave an odd number of cells).