"Update branch" still clickable, even though merge commits have been disabled

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Bug

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I've activated a branch protection rule for **/* (all) branches with ☑️ Require linear history activated. This results in the following hint and a disabled "Update with merge commit" option for updating the branch in a PR:

However, clicking on the button, without explicitly selecting "Update with rebase" first, still performs an "Update with merge commit" action.

Expected behavior
When the current branch has a branch protection rule applied with ☑️ Require linear history checked, the button for updating the branch shows "Rebase branch" by default and performs a rebase instead of creating a merge commit.

Workaround
To prevent users from accidentally creating a merge commit by clicking the "Update branch" button, the ☑️ Do not allow bypassing the above settings option can be checked in the branch protection rule. The button then still tries to perform an "Update with merge commit" action by default, but fails and an error message is being displayed instead.