The request to show the log output with more recent commits at the
bottom comes up once in a while (among Mercurial users, and now also
for jj from @arxanas). It's pretty easy to implement by adding an
adapter to the current `RevsetGraphIterator`. It works by first
collecting all nodes and edges into a vector and then yielding them in
reverse order and with reversed edges. That means it's no longer lazy,
but that seems fine since the feature is optional. Also, it's only the
subset of nodes that are in the selected revset that will be
collected.
Making the CLI use the new iterator adapter will come in a later
patch.
0747da0491