Add logic to fetch single Harvest time entry via API

for one-off imports

rattail_harvest/harvest/importing/model.py

@@ -79,6 +79,12 @@ class TimeEntryImporter(ToHarvest):
                     cache[key] = normal
         return cache
 
+    def get_single_local_object(self, key):
+        assert len(self.key) == 1 and self.key[0] == 'id'
+        entry_id = key[0]
+        if entry_id > 0:
+            return self.webapi.get_time_entry(entry_id)
+
     def normalize_local_object(self, entry):
         data = {
             'id': entry['id'],