ghc-pandoc-citeproc got removed from the distribution because it has been
deprecated, but unfortunately the latest stable release of RStudio still
requires that binary. Due to rstudio's complexity, it is pretty much impossible
to cherry-pick the patches to support the builtin citeproc functionality of
pandoc instead of pandoc-citeproc. Would it be possible to resurrect
ghc-pandoc-citeproc until the next stable release of rstudio that supports the
new pandoc release?