grub2: Generate config from pending deployment

Generate a grub2 config using the pending deployment, if a grub2
bootloader is detected in the sysroot. Allows grub2-mkconfig
to run if there are no previous deployments.

Fixes: #1774

Closes: #1831
Approved by: jlebon

src/libostree/ostree-bootloader-grub2.c

@@ -332,6 +332,7 @@ grub2_child_setup (gpointer user_data)
 static gboolean
 _ostree_bootloader_grub2_write_config (OstreeBootloader      *bootloader,
                                        int                    bootversion,
+                                       GPtrArray             *new_deployments,
                                        GCancellable          *cancellable,
                                        GError               **error)
 {
@@ -357,15 +358,11 @@ _ostree_bootloader_grub2_write_config (OstreeBootloader      *bootloader,
   if (use_system_grub2_mkconfig && ostree_sysroot_get_booted_deployment (self->sysroot) == NULL
       && g_file_has_parent (self->sysroot->path, NULL))
     {
-      g_autoptr(GPtrArray) deployments = NULL;
       OstreeDeployment *tool_deployment;
       g_autoptr(GFile) tool_deployment_root = NULL;
 
-      deployments = ostree_sysroot_get_deployments (self->sysroot);
-
-      g_assert_cmpint (deployments->len, >, 0);
-
-      tool_deployment = deployments->pdata[0];
+      g_assert_cmpint (new_deployments->len, >, 0);
+      tool_deployment = new_deployments->pdata[0];
 
       /* Sadly we have to execute code to generate the bootloader configuration.
        * If we're in a booted deployment, we just don't chroot.
@@ -380,6 +377,8 @@ _ostree_bootloader_grub2_write_config (OstreeBootloader      *bootloader,
       grub2_mkconfig_chroot = g_file_get_path (tool_deployment_root);
     }
 
+  g_debug ("Using grub2-mkconfig chroot: %s\n", grub2_mkconfig_chroot);
+
   g_autoptr(GFile) new_config_path = NULL;
   g_autoptr(GFile) config_path_efi_dir = NULL;
   if (self->is_efi)