Merge branch 'en/fast-import-parsing-fix'

"git fast-import" update.

* en/fast-import-parsing-fix:
  fast-import: fix erroneous handling of get-mark with empty orphan commits
  fast-import: only allow cat-blob requests where it makes sense
  fast-import: check most prominent commands first
  git-fast-import.txt: fix wording about where ls command can appear
  t9300: demonstrate bug with get-mark and empty orphan commits