Merge branch 'gc/fetch-negotiate-only-early-return'

Merge branch 'gc/fetch-negotiate-only-early-return'

"git fetch --negotiate-only" is an internal command used by "git
push" to figure out which part of our history is missing from the
other side.  It should never recurse into submodules even when
fetch.recursesubmodules configuration variable is set, nor it
should trigger "gc".  The code has been tightened up to ensure it
only does common ancestry discovery and nothing else.

* gc/fetch-negotiate-only-early-return:
  fetch: help translators by reusing the same message template
  fetch --negotiate-only: do not update submodules
  fetch: skip tasks related to fetching objects
  fetch: use goto cleanup in cmd_fetch()