Problem in beamer class linebreak in footline

Question

I encountered a strange definition in the footline environment of beamer. Here is a minimal example, which shows the problem:

\documentclass[hyperref={pdfpagelabels=false},rgb]{beamer}
\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{footline}{%
   \leavevmode%
   \hfill\rule{0.89\textwidth}{0.2pt}\hfill \\
   \begin{beamercolorbox}[wd=4cm,leftskip=0.5cm,sep=10pt]{page number}
    \insertframenumber
   \end{beamercolorbox}
   \hspace*{4cm}}%
\begin{document}

  \begin{frame}
  \end{frame}

\end{document}

Behind the rule there will be printed a ",". This is due to the defintion of \ \ in the footline. I have got one solution for the problem:

\setbeamertemplate{footline}{%
   \leavevmode%
   \hfill\rule{0.89\textwidth}{0.2pt}\hfill\hfill\textcolor{white}{ }
   \begin{beamercolorbox}[wd=4cm,leftskip=0.5cm,sep=10pt]{page number}
      \insertframenumber
    \end{beamercolorbox}
   \hspace*{4cm}}

Is there a better solution for that problem and why is the \ \ redefined in the footline.

Answer 1

Converting @Benjamins comment into a CW answer:

\documentclass[hyperref={pdfpagelabels=false},rgb]{beamer}
\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{footline}{%
   \leavevmode%
   \hfill\rule{0.89\textwidth}{0.2pt}\hfill\ \newline
   \begin{beamercolorbox}[wd=4cm,leftskip=0.5cm,sep=10pt]{page number}
    \insertframenumber
   \end{beamercolorbox}
   \hspace*{4cm}}%
\begin{document}

  \begin{frame}
  \end{frame}

\end{document}