reproduction repo https://github.com/dreyks/hswp_fail/tree/contenthash

Expected Behavior

Rebuilding unchanged code from cache should result in exact same file and filename

Actual Behavior

Files are same but filenames containing [contenthash] are different.

Steps to Reproduce

https://github.com/dreyks/hswp_fail/tree/contenthash

1. run yarn webpack - output: main-2f138c469b6d1cc42329.js 3.8 KiB 0 [emitted] main
2. run yarn webpack again - output: main-80bb0d27ee34d918376b.js 3.8 KiB 0 [emitted] main

Additional info

• this only happens in 'production' mode
• [chunkhash] has the same issue
• I've tried changing webpack versions and figured out that when running with webpack@4.6.0 does not produce this issue