Strange pip wheel error in pip 26.2.1

I have a setup.py based package that has a bespoke bdist_wheel class class BDistWheel(bdist_wheel): def run(self): if DEBUG: print('+++++ start BDistWheel') hgid = pjoin('src','rlextra','.hgid') with open(hgid,'w') as f: f.write(subprocess.check_output(["hg","id","-i"]).decode('ascii').replace('+','')) bdist_wheel.run(self) unwanted = pjoin(pkgDir,'rlextra.egg-info') if isdir(unwanted): if DEBUG: print(f'+++++ rmtree {unwanted!r}') shutil.rmtree(unwanted) if isfile(hgid)...