"git fetch" over protocol v2 into a shallow repository failed to
fetch full history behind a new tip of history that was diverged
before the cut-off point of the history that was previously fetched
shallowly.

* jt/upload-pack-v2-fix-shallow:
  upload-pack: clear flags before each v2 request
  upload-pack: make want_obj not global
  upload-pack: make have_obj not global