Well, the error message you are seeing is from the shell not being able to find the interpreter which is in the command shebang, so if you are having issues with commands that are using /usr/bin/env then that¹s what can¹t be found however it does seem to be in the path, so I am not really sure what is going on here. Possibly you recently added something to your shell startup files which is causing the problems?
I figured that was the problem, but I can run ruby scripts from the command line using /usr/bin/env ruby, and I've also tried editing the script in the bundle, replacing /usr/bin/env ruby with /usr/bin/ruby
I haven't made any changes to my bash files lately either, which has me perplexed.