Sed directory not found when running R with -e flag

This happens because brew has changed it's paths in this commit so if you've run brew update in the last 4 days, this is what has caused the breakage.

Credit goes to blindjesse for this answer, which is to brew reinstall -s r.

I ran into some other issues when I tried this though. I didn't have X11 installed and I had a conflict with the tcl-tk which meant that it caused some other failures when it was compiling so:

1. I installed XQuartz from https://www.xquartz.org
2. Symlinked it to my homebrew folder ln -s /opt/X11/include/X11 /usr/local/include/X11 (note that your homebrew directory may be different)
3. brew install homebrew/dupes/tcl-tk brew link --overwrite --force tcl-tk; brew unlink tcl-tk
4. brew reinstall -s r

And then it worked for me. I think once the r bottle is upgraded this issue should disappear but for the moment this is what I had to do.