The outermost "op-log" label isn't moved to the default template. I think
it belongs to the command's formatter rather than the template.
Old bikeshedding items:
- "current_head", "is_head", or "is_head_op"
=> renamed to "current_operation"
- "templates.op-log" vs "templates.op_log" (the whole template is labeled
as "op-log")
=> renamed to "op_log"
- "template-aliases.'format_operation_duration(time_range)'"
=> renamed to 'format_time_range(time_range)'