Comment 3 for bug 2017522

Cowboy deployed at UTC 1146 by @ballot.

```
diff --git a/lib/lp/archivepublisher/scripts/publishdistro.py b/lib/lp/archivepublisher/scripts/publishdistro.py
index 754c0bf3144..ea515f17dd7 100644
--- a/lib/lp/archivepublisher/scripts/publishdistro.py
+++ b/lib/lp/archivepublisher/scripts/publishdistro.py
@@ -438,7 +438,10 @@ def synchronizeSecondDirectoryWithFirst(self, first_dir, second_dir):
             copy(str(first_dir / file), str(second_dir))

         for file in files_to_delete:
- os.unlink(str(second_dir / file))
+ try:
+ os.unlink(str(second_dir / file))
+ except IsADirectoryError:
+ pass

         return bool(files_to_copy) or bool(files_to_delete)
```