bundler/bundler — pull request #3291 by kirs (2014-12-09 00:15:46+00:00)
Title: Optimized bundle-exec

(from https://trello.com/c/bf90QcsN/66-exec-as-soon-as-possible, originally it's @indirect's idea)

Right now the exec command loads the entire Gemfile, the entire lockfile, resolves the gemfile against the lockfile, and then execs. Instead, let's check $PATH for the exec command and exec instantly if it's there.