When we checked for cycles with destroy edges around providers, it was
only for providers of a different type, but one can do the same thing
with the same provider under different local aliases. Check to see if
the provider also contains an alias, or is defined absolutely in some
other way. The absolute accuracy here isn't critical, since in most
cases these edges are not required for correct results, but finding a
correct and consistent method for determining when these edges are
needed is going to take more research.
There was also an oversight fixed here where the basic
creator->destroyer edges were added _after_ the cycle checks, limiting
their utility. The ordering of the additions was swapped to make sure
all cycles are noticed.
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