Merge branch 'jk/proto-v2-hidden-refs-fix'

The v2 upload-pack protocol implementation failed to honor
hidden-ref configuration, which has been corrected.
An earlier attempt reverted out of 'next'.

* jk/proto-v2-hidden-refs-fix:
upload-pack: support hidden refs with protocol v2

diff --cc t/t5512-ls-remote.sh
Simple merge