I don't know if this is a gerrit issue or a "git cl" issue, but it's hard to figure out how to develop a patch on top of someone else's patch.

I'm working on this patch:
https://chromium-review.googlesource.com/c/chromium/src/+/634329

It requires the changes in sammc's patch:
https://chromium-review.googlesource.com/c/chromium/src/+/624772

I used "git cl patch" to make a local branch with his code. The first time I did this it warns me:

Note: this created a local commit which does not have the same hash as the one uploaded for review. This will make uploading changes based on top of this branch difficult.
If you want to do that, use "git cl patch --force" instead.

So then I patched with --force and made a new local branch on top.

But when I tried to "git cl upload" my new branch I get:

Upload upstream branch sam2 first.
It is likely that this branch has been rebased since its last upload, so you just need to upload it again.
(If you uploaded it with --no-squash, then branch dependencies are not supported, and you should reupload with --squash.)

I ended up patching in sam's change, resetting its issue number, uploading that branch as if I wrote it, then uploading my real change on top of that.

It seems like there should be a better workflow for this, or better suggestions from the tools.