--- a/checker.py	Mon Jun 13 09:54:55 2016 +0800
+++ b/checker.py	Mon Jun 13 11:08:16 2016 +0800
@@ -62,6 +62,21 @@
     if ok and not run(['hg', 'clone', config['url'], source]):
         ok = False
 
+    if ok:
+        print('$ cd {}'.format(source))
+        os.chdir(source)
+
+    if ok and not run(['hg', 'sum']):
+        ok = False
+
+    if ok:
+        template = (r'# C&O commit: {rev}:{node} {branch}\n'
+                    r'# C&O commit date: {date|isodatesec}\n'
+                    r'# C&O commit author: {author|person}\n'
+                    r'# C&O commit message: {desc|firstline}\n')
+        if not run(['hg', 'log', '-r', '.', '-T', template], silent=True):
+            ok = False
+
     print('# C&O task: cleanup')
     rmtree(tmp)