Merge branch 'dt/reflog-tests'

Tests that assume how reflogs are represented on the filesystem too
much have been corrected.

* dt/reflog-tests:
  tests: remove some direct access to .git/logs
  t/t7509: remove unnecessary manipulation of reflog

diff --cc t/t1400-update-ref.sh
Simple merge

diff --cc t/t1411-reflog-show.sh
Simple merge

diff --cc t/t3210-pack-refs.sh
Simple merge

diff --cc t/t3404-rebase-interactive.sh
Simple merge