Fix that allows strand_segments to be 1 nt long

segmentmodel.py

@@ -1269,10 +1269,10 @@ class Strand(Group):
             strand_segment_count += 1
             seg = s.segment
             contour = s.get_contour_points()
-            if s.end == s.start:
-                pdb.set_trace()
+            # if s.end == s.start:
+            #     pdb.set_trace()
             # assert(s.end != s.start)
-            assert(np.linalg.norm( seg.contour_to_position(contour[-1]) - seg.contour_to_position(contour[0]) ) > 0.1)
+            assert( s.num_nts == 1 or (np.linalg.norm( seg.contour_to_position(contour[-1]) - seg.contour_to_position(contour[0]) ) > 0.1) )
             for c,seq in zip(contour,s.get_sequence()):
                 if last is None:
                     seq = "5"+seq