Return no match if using obj.search() with an empty list of candidates. This accounts for candidate lists that are created dynamically, for example limiting them to the inventory (which may be empy). Resolves #1016.

evennia/contrib/rpsystem.py

@@ -1155,7 +1155,7 @@ class ContribRPObject(DefaultObject):
             # only allow exact matching if searching the entire database
             # or unique #dbrefs
             exact = True
-        elif not candidates:
+        elif candidates is None:
             # no custom candidates given - get them automatically
             if location:
                 # location(s) were given

evennia/objects/manager.py

@@ -357,7 +357,10 @@ class ObjectDBManager(TypedObjectManager):
                     typeclasses[i] = u"%s" % typeclass
             typeclass = typeclasses
 
-        if candidates:
+        if candidates is not None:
+            if not candidates:
+                # candidates is the empty list. This should mean no matches can ever be acquired.
+                return []
             # Convenience check to make sure candidates are really dbobjs
             candidates = [cand for cand in make_iter(candidates) if cand]
             if typeclass:

evennia/objects/objects.py

@@ -361,7 +361,7 @@ class DefaultObject(with_metaclass(TypeclassBase, ObjectDB)):
             # only allow exact matching if searching the entire database
             # or unique #dbrefs
             exact = True
-        elif not candidates:
+        elif candidates is None:
             # no custom candidates given - get them automatically
             if location:
                 # location(s) were given