\def\part@nostar@nopt#1{\NR@gettitle{#1}\titlesec@part{#1}}
\def\part@nostar@opt[#1]#2{\NR@gettitle{#1}\titlesec@part[#1]{#2}}
\makeatother
\def\part@nostar@nopt#1{\NR@gettitle{#1}\titlesec@part{#1}}
\def\part@nostar@opt[#1]#2{\NR@gettitle{#1}\titlesec@part[#1]{#2}}
\makeatother