Can't edit file using puma

Summary

Using GDK and use EXPERIMENTAL_PUMA=1 gdk run I start getting different behavior when I try to commit, with the file edit/web ide when comapred to unicorn.

Steps to reproduce

• Have the latest GDK installation
• gdk reconfigure
• EXPERIMENTAL_PUMA=1 gdk run
• Go to a repository
• Click on any file
• Click Edit button
• Do a change
• Press Commit changes

Example Project

Some of the projects GDK comes with is fine for testing.

What is the current bug behavior?

• The request is really slow
• Ends up timing out seeing the 503 error page
• The file still gets updated

What is the expected correct behavior?

• Quick response time
• Page refreshed not seeing 503 error page
• The file is updated.

Relevant logs and/or screenshots

Below is the request I am running that ends up with a 503

Output of checks

GitLab Development Kit gem version 0.2.4

/cc @andrewn