Merge branch 'dg/local-mod-error-messages'

* dg/local-mod-error-messages: t7609: test merge and checkout error messages unpack_trees: group error messages by type merge-recursive: distinguish "removed" and "overwritten" messages merge-recursive: porcelain messages for checkout Turn unpack_trees_options.msgs into an array + enum Conflicts: t/t3400-rebase.sh