[releng] convert-to-tarballs: also delete submodules

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 376c32d6a77368cba39093758329172214d5ce36
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Tue Apr 17 14:09:10 2018 -0500

    convert-to-tarballs: also delete submodules

 tools/smoketesting/convert-to-tarballs.py |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/tools/smoketesting/convert-to-tarballs.py b/tools/smoketesting/convert-to-tarballs.py
index 9f72826..85e09c6 100755
--- a/tools/smoketesting/convert-to-tarballs.py
+++ b/tools/smoketesting/convert-to-tarballs.py
@@ -658,6 +658,7 @@ class ConvertToTarballs:
         element['sources'][0]['kind'] = 'tar'
         element['sources'][0]['url'] = location
         element['sources'][0]['ref'] = sha
+        del element['sources'][0]['submodules']
         del element['sources'][0]['track']
 
         # Dump it now