Use headsepline without reducing the text body height

Question

In a document that uses the class scrreprt and the page style headings, how can a horizontal line under the header be introduced with class option headsepline=true without decreasing the text body height?

Consider the following image comparing headsepline=true and headsepline=false

As mentioned in the KOMA script documentation, the header is considered a part of the text body if headsepline=true. However, I would like to preserve the available height for text (due to a tight page limit I have to obey). With other words: how can I move the red line to the green line?

Answer 1

Use

\documentclass{scrreprt}
\KOMAoptions{headsepline,headinclude=false}

The headsepline option sets automatically headinclude=true. headinclude=false changes it back.

\documentclass{scrreprt}
\KOMAoptions{headsepline,headinclude=false}

\pagestyle{headings}

\usepackage{blindtext}% dummy text
\begin{document}
  \blinddocument
\end{document}

---

But it seems to me that there is a bug in version 3.19 because

\documentclass[headsepline,headinclude=false]{scrreprt}

should do the same and did the same in version 3.18. Update: In version 3.20 this will work again, see: Bekannte Probleme und Änderungen in KOMA-Script 3.19a (German).