The virtual links to download dropbox
https://www.dropbox.com/download
https://www.dropbox.com/download?plat=lnx.x86_64
sometimes (like once in 30 tries) redirect automatically to the latest BETA build instead of the latest STABLE build.
No clue why, but watch these for a couple of minutes and you'll probably see build 238.3.5977 appear
while true ; do curl -sI "https://www.dropbox.com/download" | grep '^location: https:' ; sleep 1.5 ; done
or
while true ; do curl -sI "https://www.dropbox.com/download?plat=lnx.x86_64" | grep '^location: https:' ; sleep 1.5 ; done