Cannot change the default base branch `main` (GraphQL: Cannot change the base branch because the pull request is part of a stack. (updatePullRequest))

This feature could be better for code management if it can be used for projects with multiple environments since I cannot change the default base branch `main` to other branches (like staging, or to break a branch into many features and merge into it for better testing)

I have tried the following
```
# In your local repo
gh pr edit --base
```
And I got
```
GraphQL: Cannot change the base branch because the pull request is part of a stack. (updatePullRequest)
```

I would love an update or explanation for this

Start by reproducing the issue with `gh pr edit --base ` and inspect the reported `updatePullRequest` GraphQL error. Determine whether stacked pull requests can support changing the base branch, then document the limitation or define the behavior needed for staging and multi-feature workflows.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.