* Revert "Always confirm before pushing the selected branch (#3)"
This reverts commit 619bbf71c7.
* Always prompt for the upstream when pushing the selected branch
A plain yes/no confirmation doesn't let the user catch or fix a wrong
target before pushing. Reuse the same upstream-entry prompt already
shown for a branch with no upstream configured, but always show it for
a selected-branch push, pre-filled with the branch's current upstream
(or a suggested one if it has none). Confirming pushes to whatever's
typed there, and re-establishes it as the branch's tracking upstream.
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Co-authored-by: Khanh Truong <khanh_t@arbin.com>