[O] [bug, ox or ob?] something leaks tabs in src blocks

[Rasmus]

Hi,

Consider the following example

* test
#+BEGIN_SRC R
  test <- function(index, funs, ...){
      if (missing(funs)) {
              funs <- list(
                  "a" = funa,
                  "b" = funb)}

      col <- vapply(funs, function(FUN) {
          do.call(FUN, list(index, ...))}, 1.0)
      col}
#+END_SRC

It includes no tabs.  When exported with ox-latex or ox-ascii, but not
ox-html, it has become something along the following, which at least at
the time of posting contains tabs.  When exporting via xelatex, tabs in
verbatim shows up as "^^I".

\begin{verbatim}
test <- function(index, funs, ...){
    if (missing(funs)) {
            funs <- list(
                "a" = funa, # not really
                "b" = funb,
                "c" = func)}

    col <- vapply(funs, function(FUN) {
        do.call(FUN, list(index, ...))}, 1.0)
    col <- pretty_num(col, rounding = TRUE)
    names(col) <- names(funs)
    col}
\end{verbatim}

Does anyone know WHERE tabs are introduced so I can try to fix this?  It
seems by the time the src element reaches at least
org-export-format-code-default it already contains tabs.

Thanks,
Rasmus

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