More fixes in objects to be downloaded

src/inventory.py

@@ -121,7 +121,6 @@ class Missing(object):
     def pull(self, count=1):
         if count < 1:
             raise ValueError("Must be at least one")
-        with self.lock:
         objectHashes = []
         try:
             for objectHash in self.hashes.keys():
@@ -134,7 +133,7 @@ class Missing(object):
                         self.removeObjectFromCurrentThread(objectHash)
                         if len(objectHashes) >= count:
                             break
-            except RuntimeError:
+        except (RuntimeError, KeyError, ValueError):
             # the for cycle sometimes breaks if you remove elements
             pass
         return objectHashes