hang on startup with 5.3.5+ and carrierwave #512
Description
After upgrading a simple Rails app from scout 5.3.3 to 5.4.0, puma now hangs on initialization. strace shows that it's spinning on a futex; the process also ignores SIGINT, which seems kind of rude (but does respond to SIGTERM). Everything works fine if starting a rails console or other interactive process; it's something unhappy between scout and puma.
Downgrading to 5.3.3 fixes the problem; upgrading to 5.3.5 or 5.4.0 reproduces it.
Bisection points to 37c88b8 as the offending commit; everything works in 679670e but and hangs in 37c88b8.
Relevant specs
Ruby: 3.3.5
Rails: 7.2.1.2