title: knitr compile problems with RStudio (windows)
body: <p>i have a knitr based Rnw file that is compiling to pdf perfectly fine in RStudio on mac (v0.97.316) and knitr (v1.1) but in a windows enviornment (same versions) i get a compilation error. I've checked the options in RStudio in both environments and they are consistent.</p>
  
  <p>It appears that the windows setup is always injecting: "\SweaveOpts{concordance=TRUE}" into the ".tex" file even though i have no such flag in the Rnw file, and/or if i toggle the settings in the preferences, and/or if i add the "opts_knit$set(concordance=FALSE)" options to a knitr settings chunk. If i drop the line from the ".tex" file and compile it manually at the cmd prompt the output is generated as expected.</p>
  
  <p>I'm not sure if this is an RStudio or knitr problem, but any pointers would be appreciated.</p>
  
  <p>Note, i've also posted this question on the RStudio support board (<a href="http://support.rstudio.org/help/discussions/problems/5039-knitr-compile-problems-with-rstudio-windows?unresolve=true" rel="nofollow">http://support.rstudio.org/help/discussions/problems/5039-knitr-compile-problems-with-rstudio-windows?unresolve=true</a>).</p>