Merge branch 'sb/format-patch-patchname'

* sb/format-patch-patchname:
  format_sanitized_subject: Don't trim past initial length of strbuf
  log-tree: fix patch filename computation in "git format-patch"
  format-patch: --numbered-files and --stdout aren't mutually exclusive
  format-patch: --attach/inline uses filename instead of SHA1
  format-patch: move get_patch_filename() into log-tree
  format-patch: pass a commit to reopen_stdout()
  format-patch: construct patch filename in one function
  pretty.c: add %f format specifier to format_commit_message()

Documentation/pretty-formats.txt

@@ -121,6 +121,7 @@ The placeholders are:
 - '%d': ref names, like the --decorate option of linkgit:git-log[1]
 - '%e': encoding
 - '%s': subject
+- '%f': sanitized subject line, suitable for a filename
 - '%b': body
 - '%Cred': switch color to red
 - '%Cgreen': switch color to green