I was looking for it, but couldn’t find it (but I also have heard, and not read about it iirc). I spent some more time checking and so far no changes to the pipe implementation have been made in 4.2 dev if I can tell correctly (usually I am not that deep into language internals). https://github.com/r-devel/r-svn/blob/master/src/main/gram.c
Edit: Also on svn https://svn.r-project.org/R/trunk/src/main/gram.c
If I get any details on this I surely will remember to post them here though.