Homebrew reports 'Found Ruby file outside tobi/try tap formula directory'

[tomhoover]

try installed on macOS using homebrew. brew doctor reports:

Warning: Found Ruby file outside tobi/try tap formula directory.
(/opt/homebrew/Library/Taps/tobi/homebrew-try/Formula):
  /opt/homebrew/Library/Taps/tobi/homebrew-try/try.rb