Reduce renumbering/reorienting done by simplify

spherogram_src/links/links_base.py

@@ -729,7 +729,15 @@ def _build(self, start_orientations=None, component_starts=None):
 
     def _rebuild(self, same_components_and_orientations=False):
         if same_components_and_orientations:
-            start_css = [comp[0] for comp in self.link_components]
+            # Hopefully we have enough of the original components left
+            # to figure out what this is.  Otherwise, new choices will
+            # be made as in the default algorithm.
+            start_css = []
+            for comp in self.link_components:
+                for cs in comp:
+                    if cs.crossing in self.crossings:
+                        start_css.append(cs)
+                        break
         self.link_components = None
         for c in self.crossings:
             c._clear()
@@ -758,6 +766,8 @@ def _orient_crossings(self, start_orientations=None):
             return
         if start_orientations is None:
             start_orientations = list()
+        else: # copy as algorithm modifies this list
+            start_orientations = list(start_orientations)
         remaining = OrderedSet(
             [(c, i) for c in self.crossings for i in range(4) if c.sign == 0])
         while len(remaining):

spherogram_src/links/simplify.py

@@ -197,7 +197,8 @@ def simplify_via_level_type_III(link, max_consecutive_failures=100):
         else:
             failures += 1
 
-    link._build_components()
+    assert link.all_crossings_oriented()
+    link._rebuild(True)
     return success
 
 
@@ -820,5 +821,5 @@ def pickup_simplify(link, type_III=0):
     # twists. We check for this only once, at the end, for speed.
     untwist_diagram(L)
 
-    L._rebuild()
+    L._rebuild(True)
     return len(L.crossings) != init_num_crossings