Merge branch 'ab/branch-sort'
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