biblatex: exclamation mark in title of bib item interferes with field separator

Question

The following code shows, that an exclamation mark in the title of a bib entry removes the field separator (here: a comma) which separates the title from the journal. How can this be avoided? If the title does not contain the exclamation mark, the comma is correctly printed.

Note: you have to run the code twice (first, bib.bib has to be generated)

\documentclass{scrartcl}

\usepackage[T1]{fontenc}
\usepackage[american]{babel}
\usepackage{blindtext}
\usepackage[
backend=bibtex,
style=authoryear,
sorting=ydnt
]{biblatex}

\usepackage{filecontents}
% remove "!" and the comma separator will be there
\begin{filecontents*}{bib.bib}
@article{mykey,
  author={TeX, L.},
  journal={Journal of LaTeX questions},
  pages={1--10},
  title={{Minimal title!}},
  volume={1},
  number={1},
  year={2011}}
\end{filecontents*}

% bibliography
\renewcommand*{\newunitpunct}{\addcomma\space}
\DeclareFieldFormat*{title}{#1}
\renewbibmacro*{in:}{}

\addbibresource{bib.bib}% bibliography data

\begin{document}
\blindtext[1]
\textcite{mykey}
\printbibliography
\end{document}

Answer 1

In my opinion, biblatex is correct in omitting the comma separator after a title that ends with a period, question mark, or exclamation mark. If you insist on adding a comma even in those cases, use a literal , instead of \addcomma:

\renewcommand*{\newunitpunct}{,\space}