unnest the hg depending tag finding code as all its asumptions are now checked by its caller
unnest the hg depending tag finding code as all its asumptions are now checked by its caller

esben/setuptools_scm,ionelmc/setuptools_scm,RonnyPfannschmidt/setuptools_scm,RonnyPfannschmidt/setuptools_scm,davidszotten/setuptools_scm,ionelmc/setuptools_scm,dstufft/setuptools_scm,untitaker/setuptools_scm,esc/setuptools_scm,pypa/setuptools_scm,esc/setuptools_scm,phargogh/setuptools_scm,untitaker/setuptools_scm,phargogh/setuptools_scm,HolgerPeters/setuptools_scm,pypa/setuptools_scm,davidszotten/setuptools_scm