Merge branch 'js/fetch-push-trace2-annotation'

More trace2 events at key points on push and fetch code paths have
been added.

* js/fetch-push-trace2-annotation:
  send-pack: add new tracing regions for push
  fetch: add top-level trace2 regions
  trace2: implement trace2_printf() for event target

diff --cc builtin/fetch.c
Simple merge