Merge branch 'master' into ph/strbuf

Merge branch 'master' into ph/strbuf

* master:
  archive - leakfix for format_subst()
  Make --no-thin the default in git-push to save server resources
  fix doc for --compression argument to pack-objects
  git-tag -s must fail if gpg cannot sign the tag.
  git-svn: understand grafts when doing dcommit
  git-diff: don't squelch the new SHA1 in submodule diffs
  Define NO_MEMMEM on Darwin as it lacks the function
  git-svn: fix "Malformed network data" with svn:// servers
  (cvs|svn)import: Ask git-tag to overwrite old tags.
  git-rebase: fix -C option
  git-rebase: support --whitespace=<option>
  Documentation / grammer nit
  archive: rename attribute specfile to export-subst
  archive: specfile syntax change: "$Format:%PLCHLDR$" instead of just "%PLCHLDR" (take 2)
  add memmem()
  Remove unused function convert_sha1_file()
  archive: specfile support (--pretty=format: in archive files)
  Export format_commit_message()