/usr/bin/fission is in ruby-fission 0.5.0-2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | #!/usr/bin/ruby
$:.unshift File.join(File.dirname(__FILE__), *%w[.. lib])
require 'fission'
Fission::CLI.new.execute
|