xpatch bug in texlive 2019?

The nomencl package has been updated recently and now it uses by default the tocbasic package.

In order to use the old method, you need to call the package with the option notocbasic.

% arara: pdflatex
% arara: nomencl
% arara: pdflatex

documentclass[]{article}
usepackage{xpatch}
usepackage[notocbasic]{nomencl} 

patchcmd{thenomenclature}{section*{nomname}}{relax}{typeout{Success}}{typeout{Failure}}
makenomenclature 

begin{document}
text
nomenclature[1]{$mu$}{variable}
printnomenclature[0.9in]
end{document}

With the tocbasic method, you have to patch tocbasic@listhead, but this might have adverse effects on other parts of the document.

documentclass[]{article}
usepackage{xpatch}
usepackage{nomencl}

makeatletter
patchcmdtocbasic@listhead{section*}{@gobble}{}{}
makeatother

makenomenclature

begin{document}
text
nomenclature[1]{$mu$}{variable}
printnomenclature[0.9in]
end{document}