Ensure the test for checking "change merge result is identical from
both upstream with carried patches and current" can be handled
correctly is building the test tree correctly using 'cherry-pick' to
duplicate the tree state.
For cherry-pick of changes to work correct, enable use of 'force
cherry-pick' through the '-x' option, to ensure a new commit is always
made instead of allowing for the possibility of a fast-forward to occur.
Include a modification to the commit message to insert the new node name
in the message (e.g "[C] Add file change" is cherry-picked as "[C1] Add
file change")
This changes exposed a random bug where the walking of the graph results
in the same node being visited twice. This in turn causes the wrong
commit id to be stored and reused to checkout the desired node when
building the tree resulting in a very broken graph.
Add a check for the _FINISHED flag being set to spot this scenario and
use this to avoid returning the same node twice in the topological
sorted graph, which in turn ensures that we do not accidentally
recreate a second commit for the same node, replacing the original node.
Change-Id: Ie1ae27196b3616979826e2df72df3cb7a517475d
e4190ff279