Merge branch 'jk/fetch-follow-remote-head-fix'

Merge branch 'jk/fetch-follow-remote-head-fix'

"git fetch [<remote>]" with only the configured fetch refspec
should be the only thing to update refs/remotes/<remote>/HEAD,
but the code was overly eager to do so in other cases.

* jk/fetch-follow-remote-head-fix:
  fetch: make set_head() call easier to read
  fetch: don't ask for remote HEAD if followRemoteHEAD is "never"
  fetch: only respect followRemoteHEAD with configured refspecs