[Rd] R license: GPL v2 or v3?

[Gabriel Gellner]

For a project I am porting some of R's source code, and I want to
get the license for my project correct, but the top level COPYING file
for R's source states GPL v2, but when using:

    > license()

(which also states GPL version 2) points me towards:

    > RShowDoc('COPYING')

which states GPL v3. Which is correct?

Thanks for clarification (and the amazing amount of code!).

Gabriel