hooks.add_entity: Maintain sequences of name prefixes.

import2ledger/hooks/add_entity.py

@@ -43,12 +43,16 @@ class AddEntityHook:
 
     def _str2entity(self, s, trim_re, name_shifts):
         parts = list(self._entity_parts(s, trim_re))
-        if not parts:
-            return ''
-        for _ in range(name_shifts):
-            parts.insert(0, parts.pop())
-        if parts[-1].lower() in self.NAME_PREFIXES:
-            parts.insert(0, parts.pop())
+        if name_shifts > 0:
+            pivot = -name_shifts - 1
+            try:
+                while parts[pivot].lower() in self.NAME_PREFIXES:
+                    pivot -= 1
+            except IndexError:
+                pass
+            else:
+                pivot += 1
+                parts = parts[pivot:] + parts[:pivot]
         return '-'.join(parts)
 
     def _name2entity(self, name, name_shifts):