Merge branch 'js/rebase-helper'

"git rebase -i" starts using the recently updated "sequencer" code.

* js/rebase-helper:
rebase -i: use the rebase--helper builtin
rebase--helper: add a builtin helper for interactive rebases

diff --combined Makefile
index a5433978e3714fb9a37273e07fb235ea6d63d31b,29f8663509416777e036fc43c9f67155bd7cbb26..9ec6065cc28310d93b5bbcfb5c3146405c319f6c
--- 1/Makefile
--- 2/Makefile
+++ b/Makefile
@@@ -781,7 -781,6 +781,7 @@@ LIB_OBJS += notes-cache.
  LIB_OBJS += notes-merge.o
  LIB_OBJS += notes-utils.o
  LIB_OBJS += object.o
 +LIB_OBJS += oidset.o
  LIB_OBJS += pack-bitmap.o
  LIB_OBJS += pack-bitmap-write.o
  LIB_OBJS += pack-check.o
@@@ -933,6 -932,7 +933,7 @@@ BUILTIN_OBJS += builtin/prune.
  BUILTIN_OBJS += builtin/pull.o
  BUILTIN_OBJS += builtin/push.o
  BUILTIN_OBJS += builtin/read-tree.o
+ BUILTIN_OBJS += builtin/rebase--helper.o
  BUILTIN_OBJS += builtin/receive-pack.o
  BUILTIN_OBJS += builtin/reflog.o
  BUILTIN_OBJS += builtin/remote.o