are_mergeable 0 0 FALSE
are_mergeable 0 2 FALSE
are_mergeable 0 1 FALSE
are_mergeable 1 0 FALSE
#
are_mergeable 4 4 FALSE
are_mergeable 4 6 FALSE
are_mergeable 4 5 FALSE
are_mergeable 5 4 FALSE
#
are_mergeable 0 8 FALSE
#
# precondition violation! merge 4 5 7
# precondition violation! merge 0 8 9
