Merge branch 'ds/doc' into jc/fmt-patch

* ds/doc:
  Update documentation for git-format-patch
  sha1_file: avoid re-preparing duplicate packs
  handle concurrent pruning of packed objects
  http: prevent segfault during curl handle reuse
  Remove possible segfault in http-fetch.
  gitk: show_error fix
  [PATCH] gitk: start-up bugfix
  [PATCH] gitk: Replace "git-" commands with "git "
  [PATCH] gitk: Display commit messages with word wrap
  gitk: Fix bug where page-up/down wouldn't always work properly
  gitk: Fix display of "(...)" for parents/children we haven't drawn
  send-email: only 'require' instead of 'use' Net::SMTP
  Allow multiple -m options to git-commit.