Assignment fails due to duplicate taxonomic rank entries

[johnne]

Entries that have multiple definitions at a certain rank causes contigtax assign to fail with the error:

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

For instance, this can be the result of a taxonomic id having:

rank   superkingdom phylum order genus species  class  family    class
182248         2759   7711  9443  9499   30589  40674  378855  1338369

This will be fixed in the next release by only selecting unique columns when setting up the lineage dataframe.