if all internal branch lengths are 1, we should get a distance of 4 between nodes 5 and 0 (due to the missing internal ranks), but now after 428cd05, this will be set to:
1 if branch_length_fun=lambda x: 1
5 if branch_length_fun=lambda x: x
and so a new option will need to be provided to recover the old behavior of setting all internal branch lengths to 1.
Due to changes in 428cd05, the old default of setting all branch lengths to 1 resulted in things like the following. For this profile:
if all internal branch lengths are 1, we should get a distance of 4 between nodes 5 and 0 (due to the missing internal ranks), but now after 428cd05, this will be set to:
branch_length_fun=lambda x: 1
branch_length_fun=lambda x: x
and so a new option will need to be provided to recover the old behavior of setting all internal branch lengths to 1.