Merge branch 'hn/allow-bogus-oid-in-ref-tests'

The test helper for refs subsystem learned to write bogus and/or
nonexistent object name to refs to simulate error situations we
want to test Git in.

* hn/allow-bogus-oid-in-ref-tests:
  t1430: create valid symrefs using test-helper
  t1430: remove refs using test-tool
  refs: introduce REF_SKIP_REFNAME_VERIFICATION flag
  refs: introduce REF_SKIP_OID_VERIFICATION flag
  refs: update comment.
  test-ref-store: plug memory leak in cmd_delete_refs
  test-ref-store: parse symbolic flag constants
  test-ref-store: remove force-create argument for create-reflog

diff --cc refs.c
Simple merge

diff --cc refs.h
Simple merge

diff --cc refs/files-backend.c
Simple merge

diff --cc t/helper/test-ref-store.c
Simple merge

diff --cc t/t1405-main-ref-store.sh
Simple merge