Cannot run named process type when using --exit-code

[schneems]

Expected: Running heroku run <cmd> functions the same as heroku run <cmd> --exit-code but the exit code $? is preserved.

Actual:

$ cat Gemfile
source 'https://rubygems.org'
gem 'rake'
$ cat Gemfile.lock
GEM
  remote: https://rubygems.org/
  specs:
    rake (13.2.1)

PLATFORMS
  arm64-darwin-24
  ruby

DEPENDENCIES
  rake

BUNDLED WITH
   2.6.6
$ cat Procfile
yolo: echo "yolo"
$ heroku run yolo
Running yolo on ⬢ sheltered-savannah-90249... up, run.9872
yolo
$ heroku run yolo --exit-code
Running yolo on ⬢ sheltered-savannah-90249... up, run.7971
/bin/bash: line 1: yolo: command not found

 ›   Error: Process exited with code 127
 ›   Code: 127

This seems to only happen when using commands that are defined by a buildpack or the Procfile. In this case yolo is defined in the Procfile.

This issue affects users of integration testing library heroku_hatchet which sets this flag by default https://github.com/heroku/hatchet/blob/1cbbf7f0b482d466bfd32a4cacbc3177010dab97/lib/hatchet/heroku_run.rb#L122C48-L122C57