[Rd] Wishlist: browser and traceback should trim callstack when printing (PR#8638)

[h.wickham@gmail.com]

Full_Name: Hadley Wickham
Version: 2.2.0
OS: OS X
Submission from: (NULL) (129.186.195.213)


Example: 

f <- function(...) browser()
do.call(f, mtcars)

Entire contents of mtcars is printed on callstack.  

When you are using do.call with large data.frames this is a frustrating as it
easily wipes out your entire buffer.  While it is useful to be able to see all
the arguments when looking for the cause of the bug, manual inspection is
impractical when dealing with very long arguments.