Oops, actually, my path did get messed up. I didn't notice before
(must be Monday), but there are several directories missing from the
PATH, including the /scripts directory. So I just did another test:

     /scripts/script2.rb:
          #!/usr/bin/ruby
          puts `env | grep PATH`
          puts ENV["PATH"]
          puts `/usr/bin/env | grep PATH`

     Command Line:
          [testing]% script2.rb
          /bin:/usr/bin:/usr/local/bin:.:/scripts
          /bin:/usr
          PATH=/bin:/usr
          [testing]%

And I notice that there is no "/usr" initially, but it's there after
the ENV["PATH"] is referenced. I've searched all the files in my home
directory, and don't see it setting just "/usr" to the path anywhere.
I also search through the files in the Ruby directory, and also never
see a "/usr" by itself.