[releng] convert-to-tarballs: Be more careful about replacing sources

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 9fde2765dd2df85a3bdee10a34e1157dd04ce520
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Tue Apr 17 14:03:24 2018 -0500

    convert-to-tarballs: Be more careful about replacing sources
    
    We are clobbering second source in polkit.bst, which is not supposed to
    be touched. This is slightly tricky to fix because we have to preserve
    the original order or BuildStream will complain.

 tools/smoketesting/convert-to-tarballs.py |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)
---
diff --git a/tools/smoketesting/convert-to-tarballs.py b/tools/smoketesting/convert-to-tarballs.py
index ea8acb3..9f72826 100755
--- a/tools/smoketesting/convert-to-tarballs.py
+++ b/tools/smoketesting/convert-to-tarballs.py
@@ -654,14 +654,11 @@ class ConvertToTarballs:
         return location, version, hash, size
 
     def write_bst_file(self, fullpath, element, location, sha):
-        #
-        # Replace the source list with one tarball
-        #
-        element['sources'] = [{
-            'kind': 'tar',
-            'url': location,
-            'ref': sha
-        }]
+        # Replace the first source with a tarball
+        element['sources'][0]['kind'] = 'tar'
+        element['sources'][0]['url'] = location
+        element['sources'][0]['ref'] = sha
+        del element['sources'][0]['track']
 
         # Dump it now
         with open(fullpath, 'w') as f: