Merge branch 'jt/transport-hide-vtable'

Code clean-up.

* jt/transport-hide-vtable:
  transport: make transport vtable more private
  clone, fetch: remove redundant transport check

diff --cc builtin/clone.c
Simple merge

diff --cc builtin/fetch.c
Simple merge

diff --cc transport-helper.c
Simple merge

diff --cc transport.c
Simple merge