It took me a little while to find a solution for this, so I thought I’d post it.
I was cleaning some deployment dirs and wanted, just for this instance, to only leave 1 release as opposed to the 5 releases that capistrano leaves by default. Keep in mind this was across about 6 apps and 2 stages for each.
Option 1: Add the following to the deploy.rb files:
set :keep_releases, 1
That would require changing them all back afterwards.
Options 2: Set the capistrano variable from the command line:
cap deploy:cleanup -s keep_releases=1