--- a/checker.py	Sat Jul 02 16:08:10 2016 +0800
+++ b/checker.py	Sun Jul 03 23:00:17 2016 +0800
@@ -64,16 +64,22 @@
 
 
 def execute(config):
-    ok = True
-
     print('# C&O job started: {}'.format(now()))
     tmp = mkdtemp(prefix='candolint.')
     os.chdir(tmp)
 
-    print('# C&O task: clone')
-    print('# C&O project URL: {}'.format(config['url']))
+    ok = True
     source = './source'
 
+    if 'url' not in config:
+        print("# C&O config doesn't have url defined.")
+        print('# C&O job failed')
+        ok = False
+
+    if ok:
+        print('# C&O task: clone')
+        print('# C&O project URL: {}'.format(config['url']))
+
     if ok and not run(['hg', 'clone', config['url'], source]):
         ok = False