jennybc

We set up knitr so it doesn't catch errors, then set
`options(error=recover)` to set up R's debug-on-error machinery.

We have to do one additional thing, before the options call though: 
trace the recover function with`sink(NULL)` to turn off the output 
capturing so the R console is useful when the debugging framework 
dumps us back into it. This has to happen before the options call
because that call grabs the `recover` object and stores it somewhere
so setting a trace on recover after the call won't affect the cached
version that gets called upon an error.

jennybc

#rm(list=ls())
library(git2r)
library(plyr)
library(daff)

differ = function(file1, file2){
  path <- tempfile(pattern="git2r-")
  dir.create(path)
  repo <- init(path)