diff -r 7629902e7554 -r 8e46ed1a0b8a server/migractions.py
--- a/server/migractions.py	Fri Sep 11 15:29:25 2015 +0200
+++ b/server/migractions.py	Fri Sep 11 15:50:29 2015 +0200
@@ -207,7 +207,7 @@
             print('-> no backup done.')
             return
         open(backupfile,'w').close() # kinda lock
-        os.chmod(backupfile, 0600)
+        os.chmod(backupfile, 0o600)
         # backup
         source = repo.system_source
         tmpdir = tempfile.mkdtemp()