Find a better way to prepare the stable branches

This was discovered at #28 (comment 557650781)

The current process using rebase can cause conflicts. I think cherry-picking is likely to cause the same conflicts as well. We should probably find a way with merge so Git will know how those conflicts were resolved in the past.

For now we just resolved the conflicts and move on, but we should find a better way in the future.

Current conclusion:

Edited by Lin Jen-Shin