Work around the f39 toolbox container not existing

On Rawhide, just use an f38 toolbox container for now.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

lib/utils.pm

@@ -479,7 +479,7 @@ sub setup_workaround_repo {
     my %workarounds = (
         "36" => [],
         "37" => [],
-        "38" => ["FEDORA-2023-ad52b2e4b9", "FEDORA-2023-ade2a4ec02"],
+        "38" => ["FEDORA-2023-ad52b2e4b9", "FEDORA-2023-ade2a4ec02", "FEDORA-2023-965f517da3"],
     );
     # then we'll download each update for our release:
     my $advortasks = $workarounds{$version};
@@ -582,7 +582,13 @@ sub _repo_setup_updates {
     assert_script_run "cd /mnt/update_repo";
     # on CANNED, we need to enter the toolbox at this point
     if (get_var("CANNED")) {
-        type_string "toolbox -y enter\n";
+        my $tboxcmd = "toolbox -y enter";
+        # FIXME there's no f39 toolbox container yet:
+        # https://github.com/containers/toolbox/issues/1233
+        # drop this workaround when that's fixed
+        $tboxcmd .= " -r 38" if (get_var("VERSION") eq get_var("RAWREL"));
+        type_string "$tboxcmd\n";
+
         # look for the little purple dot
         assert_screen "console_in_toolbox", 180;
     }