JFTR: This is already fixed in zsh 5.5.1-1ubuntu1 in cosmic (as that commit was included in the upstream 5.5.1 release).
So technically this is "fixed" in Ubuntu (generally). But since the request is explicitly for Ubuntu 18.04, someone with the proper permissions should update the "Affects" field accordingly.
JFTR: This is already fixed in zsh 5.5.1-1ubuntu1 in cosmic (as that commit was included in the upstream 5.5.1 release).
So technically this is "fixed" in Ubuntu (generally). But since the request is explicitly for Ubuntu 18.04, someone with the proper permissions should update the "Affects" field accordingly.