Merge branch 'ab/branch-sort' into maint

The implementation of "git branch --sort" wrt the detached HEAD display has always been hacky, which has been cleaned up. * ab/branch-sort: branch: show "HEAD detached" first under reverse sort branch: sort detached HEAD based on a flag ref-filter: move ref_sorting flags to a bitfield ref-filter: move "cmp_fn" assignment into "else if" arm ref-filter: add braces to if/else if/else chain branch tests: add to --sort tests branch: change "--local" to "--list" in comment