parse_Rd raises error when example section contains a quoted percent character

I was writing Rd documentation for a new package when I came across
this issue. Here's the smallest example:

library(tools)
cat("\\examples{x <- '<%=rnorm(1)%>'}\n",file=file.path(tempdir(),'test.Rd'))
readLines(file.path(tempdir(),'test.Rd'))

[1] "\\examples{x <- '<%=rnorm(1)%>'}"

parse_Rd(file.path(tempdir(),'test.Rd'))

Error in parse_Rd(file.path(tempdir(), "test.Rd")) :
 Unexpected end of input (in ' quoted string opened at test.Rd:1:17)
In addition: Warning message:
In parse_Rd(file.path(tempdir(), "test.Rd")) :
 newline within quoted string at test.Rd:1

If I take out the percent characters, parse_Rd succeeds:

cat("\\examples{x <- '<=rnorm(1)>'}\n",file=file.path(tempdir(),'test.Rd'))
parse_Rd(file.path(tempdir(),'test.Rd'))

\examples{x <- '<=rnorm(1)>'}

So is this intended behavior or a bug? I would like to use the percent
sign in a quoted string as it is part of brew syntax, and I'm writing
example code to demonstrate such.

sessionInfo()

R version 2.13.0 RC (2011-04-12 r55422)
Platform: i686-pc-linux-gnu (32-bit)

locale:
[1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=C              LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8       LC_NAME=C
[9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] tools     stats     graphics  grDevices datasets  utils     methods
[8] base

Jeff
-- 
http://biostat.mc.vanderbilt.edu/JeffreyHorner