HMR reverts 1st file after refreshing 2nd file

[gaberogan]

When using HMR, I can only work with one file at a time without fully refreshing the page.

1. When I make changes to one file, it refreshes as expected.
2. When I make changes to a second file, it updates that file but forgets the changes I made to the first file.

When I fully refresh the page, it goes back to normal.

I looked for other issues like this one but I couldn't find any. It would be great if someone can shed some light on this. It should be pretty easy to reproduce but I'm willing to provide a reproduction if necessary. It reproduces very consistently for me.