Extend vertical line in polynom division

Expanding upon Ulrike's patch to automate the process. Here, with \mypolylongdiv, the \polylongdiv is done twice for each problem, the first time to measure the drop height of the line and the 2nd time to apply it.

\documentclass[12pt,a4paper]{article}
\usepackage{polynom,xpatch}

\newlength\mypolydepth

\makeatletter
\xpatchcmd\pld@ArrangeResult{\vrule height 2.25ex}{\rule{0pt}{2.2ex}\smash{\vrule height 2.25ex depth \mypolydepth}}{}{\fail}
\makeatother 

\newcommand\mypolylongdiv[3][style=D]{%
  \setlength\mypolydepth{0pt}%
  \setbox0=\hbox{\polylongdiv[#1]{#2}{#3}}%
  \setlength\mypolydepth{\dimexpr\dp0-1.3\baselineskip}%
  \polylongdiv[#1]{#2}{#3}%
}
\begin{document}
\mypolylongdiv{x^2-4}{x+2}\medskip

\mypolylongdiv{x^3+x^2-4}{x+2}\medskip

\mypolylongdiv{x^4+x^2-4}{x+2}
\end{document}

I can make the line longer but I see no easy way to get the needed length automatically:

\documentclass[12pt,a4paper]{article}
\usepackage{polynom,xpatch}

\newlength\mypolydepth

\makeatletter
\xpatchcmd\pld@ArrangeResult{\vrule height 2.25ex}{\rule{0pt}{2.2ex}\smash{\vrule height 2.25ex depth \mypolydepth}}{}{\fail}
\makeatother 

\setlength\mypolydepth{6\baselineskip} %manual value


\begin{document}

\polylongdiv[style=D]{x^3+x^2-4}{x+2}

\end{document}