[releng/abderrahim/fix-16] convert-to-tarballs: don't crash if no version satisfies the limit

[Abderrahim Kitouni <akitouni src gnome org>]

commit da9504d0604cb427e01ab1036054f1c1c48b4605
Author: Abderrahim Kitouni <akitouni gnome org>
Date:   Wed Jun 24 16:42:09 2020 +0100

    convert-to-tarballs: don't crash if no version satisfies the limit
    
    Fixes #16

 tools/smoketesting/downloadsites.py | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/tools/smoketesting/downloadsites.py b/tools/smoketesting/downloadsites.py
index 52cb0b8..c50138b 100644
--- a/tools/smoketesting/downloadsites.py
+++ b/tools/smoketesting/downloadsites.py
@@ -113,6 +113,9 @@ class GNOME(DownloadSite):
         versions = resp.json()[1][modulename]
         latest = get_latest_version(versions.keys(), max_version)
 
+        if not latest:
+            return None, None, None
+
         extensions = ['tar.xz', 'tar.bz2', 'tar.gz']
         for ext in extensions:
             if ext in versions[latest]: