Merge Method as a Group setting
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### Proposal
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It would be convenient to make the merge method setting {Merge commit, merge commit with semi-linear history, Fast-forward merge} a group level setting.
The group level setting would be the default setting for all projects in the group. To support pushing the setting to all projects in the group, there could be an Apply-To-All-Projects setting that would individually override the Merge method project setting on each project.
OR
Make the setting be applied group-wide and remove the ability to change it on a per project basis if the group setting is specified.
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