Merge branch 'rs/wt-status-detached-branch-fix' into maint

"git status --branch --short" accessed beyond the constant string "HEAD", which has been corrected. * rs/wt-status-detached-branch-fix: wt-status: use skip_prefix() to get rid of magic string length constants wt-status: don't skip a magical number of characters blindly wt-status: avoid building bogus branch name with detached HEAD wt-status: exit early using goto in wt_shortstatus_print_tracking() t7060: add test for status --branch on a detached HEAD