Merge branch 'fc/git-complete-helper' into fc/git-prompt-script

Merge branch 'fc/git-complete-helper' into fc/git-prompt-script

By Michael Haggerty (17) and others
via Junio C Hamano (36) and Jeff King (1)
* fc/git-complete-helper: (54 commits)
  completion: add new __git_complete helper
  Update draft release notes to 1.7.11 (11th batch)
  Git 1.7.10.2
  document submdule.$name.update=none option for gitmodules
  The tenth batch of topics
  Update draft release notes to 1.7.10.2
  checkout: do not corrupt HEAD on empty repo
  apply: remove lego in i18n string in gitdiff_verify_name
  dir: convert to strbuf
  status: refactor colopts handling
  status: respect "-b" for porcelain format
  status: fix null termination with "-b"
  status: refactor null_termination option
  commit: refactor option parsing
  Documentation/git-config: describe and clarify "--local <file>" option
  reflog-walk: tell explicit --date=default from not having --date at all
  clone: fix progress-regression
  grep.c: remove redundant line of code
  checkout (detached): truncate list of orphaned commits at the new HEAD
  t2020-checkout-detach: check for the number of orphaned commits
  ...