reprint source info missing from reference listing when source entry is "inproceedings" and editor field is present

[npearlmu]

Perhaps related to #243, when the source of a reprinted book chapter is a conference proceedings paper (an "inproceedings" bibtex entry), the reprinted-from component of the output reference entry is shown as "(Reprinted from )" if the source bibtex entry includes an "editor" field. If no editor field is present, the reprinted-from information is shown correctly. (The in-text citation still correctly shows the source's date as well as the reprint's date, however, regardless of the presence of the editor field.)

Correct behavior should be to show the reprinted-from info correctly in the reference entry, including the editor when the latter is present.

MWE:

\documentclass[10pt,man,biblatex]{apa7}
\usepackage[american]{babel}
\usepackage{csquotes}
\usepackage[backend=biber, style=apa]{biblatex}

\begin{filecontents}{\jobname.bib}
@inproceedings{Amarel1968,
  title = {On Representations of Problems},
  booktitle = {Proceedings of blah blah},
  editor = {Michie, Donald},
  author = {Amarel, Saul},
  date = {1968},
  pages = {131--171},
  publisher = {Edinburgh Univ.},
}

@inproceedings{xAmarel1968,
  title = {On Representations of Problems},
  booktitle = {Proceedings of blah blah},
  author = {Amarel, Saul},
  date = {1970},
  pages = {131--171},
  publisher = {Edinburgh Univ.},
}

@incollection{Amarel1981,
  title = {On Representations},
  booktitle = {Readings in {{AI}}},
  author = {Amarel, Saul},
  editor = {Webber, Bonnie Lynn},
  date = {1981},
  pages = {2--22},
  publisher = {Morgan Kaufmann},
  related = {Amarel1968},
  relatedtype = {reprintfrom}
}

@incollection{xAmarel1981,
  title = {On Representations},
  booktitle = {Readings in {{AI}}},
  author = {Amarel, Saul},
  editor = {Webber, Bonnie Lynn},
  date = {1981},
  pages = {2--22},
  publisher = {Morgan Kaufmann},
  related = {xAmarel1968},
  relatedtype = {reprintfrom}
}
\end{filecontents}

\addbibresource{\jobname.bib}

\title{Brief Article}
\shorttitle{Brief Article}

\begin{document}
REPRINTS: \autocite{Amarel1981}, \autocite{xAmarel1981}
\printbibliography
\end{document}