Knitr doesn't seem to gracefully tidy hashes, e.g.: a<-'#'

Question

How do I use knitr to tidy code including hash signs?

\documentclass{article}
\begin{document}
<<hash>>=
# Set 'a' to an octothorpe or hash sign: 
a<-'#' 
@ 
\end{document}

With purl I get an Warning and Error like this:

...
Warning in block_exec(params) :
  failed to tidy R code in chunk <hash>
reason: Error in base::parse(text = text, srcfile = NULL) :   
  2:30: unexpected INCOMPLETE_STRING
2: a<-' %InLiNe_IdEnTiFiEr% "#' "
...

The generated LaTeX and pdf look OK, but the warning is disconcerting.

I'm using ESS within Aquamacs on a Mac.

Answer 1

Using double quotes fixes the problem for me

\documentclass{article}
\begin{document}
<<hash>>=
# Set 'a' to an octothorpe or hash sign: 
a<-"#" 
@ 
\end{document}

Seems like a bug with formatR though.