I edited my commit message, but when I `git cl upload`ed new patch sets, the old one came back. I'm a bit scared of what'll happen when I try to commit my change.

Patch set 4 is where I edited the commit message:

  https://chromium-review.googlesource.com/c/chromium/src/+/639670/4

...and in the current patch set view (6, as of this writing), it shows the old commit message:

  https://chromium-review.googlesource.com/c/chromium/src/+/639670