Ignore tree indices when deciding if things are in-sync if the user provides order-trees to acmd diff-root
This fixes ATEAM-546. When we compare files w/ shuffled tree indices we shouldn't compare tree indices to decide if things are in-sync or not (since indices are obviously different). This essentially only changes the error messages and not the result of the test, which was anyhow correct.
I also updated the message to:
old_index.new_index.branch/variable_name old_value -> new_value => diff= [diff%]
to improve it.
BTW if the user doesn't provide --order-trees
to acmd diff-root
they won't notice anything.
cc: @jchapman