Always sign the appstream commit, even if it didn't change

This means if nothing changed, but you added (or changed) the
gpg key we still sign the old commit, which we otherwise
don't since we completely ignore the change.

common/flatpak-utils.c

@@ -3528,6 +3528,7 @@ flatpak_repo_generate_appstream (OstreeRepo   *repo,
       g_autoptr(GFile) root = NULL;
       g_autoptr(OstreeMutableTree) mtree = NULL;
       g_autofree char *commit_checksum = NULL;
+      g_autofree char *parent_commit_checksum = NULL;
       OstreeRepoTransactionStats stats;
       g_autoptr(OstreeRepoCommitModifier) modifier = NULL;
       g_autofree char *parent = NULL;
@@ -3608,7 +3609,7 @@ flatpak_repo_generate_appstream (OstreeRepo   *repo,
         {
           g_autoptr(GFile) parent_root;
 
-          if (!ostree_repo_read_commit (repo, parent, &parent_root, NULL, cancellable, error))
+          if (!ostree_repo_read_commit (repo, parent, &parent_root, &parent_commit_checksum, cancellable, error))
             goto out;
 
           if (g_file_equal (root, parent_root))
@@ -3633,34 +3634,45 @@ flatpak_repo_generate_appstream (OstreeRepo   *repo,
                                              &commit_checksum, cancellable, error))
                 goto out;
             }
+        }
+      else
+        {
+          ostree_repo_abort_transaction (repo, cancellable, NULL);
+          commit_checksum = g_strdup (parent_commit_checksum);
+        }
 
-          if (gpg_key_ids)
-            {
-              int i;
+      /* Always sign commit, it may not have changed but we have a new gpg key */
+      if (gpg_key_ids)
+        {
+          int i;
 
-              for (i = 0; gpg_key_ids[i] != NULL; i++)
+          for (i = 0; gpg_key_ids[i] != NULL; i++)
+            {
+              const char *keyid = gpg_key_ids[i];
+              g_autoptr(GError) my_error = NULL;
+
+              if (!ostree_repo_sign_commit (repo,
+                                            commit_checksum,
+                                            keyid,
+                                            gpg_homedir,
+                                            cancellable,
+                                            &my_error) &&
+                  /* Ignore if the signature already exists */
+                  !g_error_matches (my_error, G_IO_ERROR, G_IO_ERROR_EXISTS))
                 {
-                  const char *keyid = gpg_key_ids[i];
-
-                  if (!ostree_repo_sign_commit (repo,
-                                                commit_checksum,
-                                                keyid,
-                                                gpg_homedir,
-                                                cancellable,
-                                                error))
-                    goto out;
+                  g_propagate_error (error, g_steal_pointer (&my_error));
+                  goto out;
                 }
             }
+        }
 
+      if (!skip_commit)
+        {
           ostree_repo_transaction_set_ref (repo, NULL, branch, commit_checksum);
 
           if (!ostree_repo_commit_transaction (repo, &stats, cancellable, error))
             goto out;
         }
-      else
-        {
-          ostree_repo_abort_transaction (repo, cancellable, NULL);
-        }
     }
 
   return TRUE;