Fix is_set to return True for falsy values inside dictionaries

Signed-off-by: Jeff Casavant <[email protected]>

tests/test_vyper.py

@@ -25,6 +25,10 @@
 
 yaml_example = """Hacker: true
 name: steve
+pets:
+    count: 0
+    names: []
+    preferred_veterinarian: ''
 hobbies:
 - skateboarding
 - snowboarding
@@ -430,6 +434,9 @@ def test_unmarshall(self):
     def test_is_set(self):
         self.v.set_config_type("yaml")
         self.v.read_config(yaml.safe_dump(text(yaml_example)))
+        self.assertTrue(self.v.is_set("pets.count"))
+        self.assertTrue(self.v.is_set("pets.names"))
+        self.assertTrue(self.v.is_set("pets.preferred_veterinarian"))
         self.assertTrue(self.v.is_set("clothing.jacket"))
         self.assertFalse(self.v.is_set("clothing.jackets"))
         self.assertFalse(self.v.is_set("helloworld"))

vyper/vyper.py

@@ -167,7 +167,7 @@ def _search_dict(self, d, keys):
             return d
         for key in keys:
             val = self._find_insensitive(key, d)
-            if val and not isinstance(val, dict):
+            if val is not None and not isinstance(val, dict):
                 return val
             elif val:
                 return self._search_dict(val, keys[1::])