Merge branch 'mm/fetch-show-error-message-on-unadvertised-object'

Merge branch 'mm/fetch-show-error-message-on-unadvertised-object'

"git fetch" that requests a commit by object name, when the other
side does not allow such an request, failed without much
explanation.

* mm/fetch-show-error-message-on-unadvertised-object:
  fetch-pack: add specific error for fetching an unadvertised object
  fetch_refs_via_pack: call report_unmatched_refs
  fetch-pack: move code to report unmatched refs to a function