[BioPython] Bio.PDB : model count in NMR structures

[K. Arun]

Hello,

In the course of extracting sequence information for  a sub-set of PDB
files and writing out specific parts using the Bio.PDB classes, I ran
across an anomaly.  When parsing NMR structures, if I query the number
of models present in the structure thus :

str = p.get_structure('8tfv', '8tfv.pdb')
mdls = Selection.unfold_entities(str, 'M')

print len(mdls)

, the number of models printed always exceeds the number present in
the file by 1. A mdls[-1].get_list() yields an empty chain list. Is
this a known issue, or even, a feature ?

-arun