Merge branch 'di/fast-import-ident'

* di/fast-import-ident:
  fsck: improve committer/author check
  fsck: add a few committer name tests
  fast-import: check committer name more strictly
  fast-import: don't fail on omitted committer name
  fast-import: add input format tests

diff --cc Documentation/git-fast-import.txt
Simple merge

diff --cc fast-import.c
Simple merge

diff --cc t/t9300-fast-import.sh
Simple merge