checks in get_latest_roots that all IDs are current

[ilexaquifolium]

In some cases where a change has been made to a non-current version of the neuron, IDs that are not current IDs can be returned by get_latest_roots(). Example:

>>> client = caveclient.CAVEclient('fanc_production_mar2021')
>>> roots = client.chunkedgraph.get_latest_roots(648518346511326005)
>>> roots
array([648518346490738685, 648518346490090970, 648518346487824596,
       648518346478115029, 648518346491690920, 648518346493870449,
       648518346494682679, 648518346496428629, 648518346486444448,
       648518346467095022, 648518346504152360, 648518346494330759,
       648518346499567451])
>>> client.chunkedgraph.is_latest_roots(roots)
array([ True,  True,  True,  True,  True,  True, False,  True,  True,
       False,  True,  True,  True])

this can lead to suggest_latest_roots() also suggesting an ID that is not current:

>>> client.chunkedgraph.suggest_latest_roots(648518346511326005)
648518346494682679
>>> client.chunkedgraph.is_latest_roots(648518346494682679)
array([False])

This small alteration adds a check for these IDs and removes them.

[fcollman]

Thanks for this, i'm going to look into these examples to make sure that I understood what went wrong in this case. I don't want to add another round trip call that slows things down when there could be a fix applied to the backend code instead.