Merge branch 'es/format-patch-interdiff'

"git format-patch" learned a new "--interdiff" option to explain
the difference between this version and the previous atttempt in
the cover letter (or after the tree-dashes as a comment).

* es/format-patch-interdiff:
  format-patch: allow --interdiff to apply to a lone-patch
  log-tree: show_log: make commentary block delimiting reusable
  interdiff: teach show_interdiff() to indent interdiff
  format-patch: teach --interdiff to respect -v/--reroll-count
  format-patch: add --interdiff option to embed diff in cover letter
  format-patch: allow additional generated content in make_cover_letter()

diff --cc Makefile
index 7cf6820,b268519..b567ccc
--- 1/Makefile
--- 2/Makefile
+++ b/Makefile
@@@ -884,7 -871,7 +884,8 @@@ LIB_OBJS += linear-assignment.
  LIB_OBJS += help.o
  LIB_OBJS += hex.o
  LIB_OBJS += ident.o
+ LIB_OBJS += interdiff.o
 +LIB_OBJS += json-writer.o
  LIB_OBJS += kwset.o
  LIB_OBJS += levenshtein.o
  LIB_OBJS += line-log.o

diff --cc builtin/log.c
index 517c5e6,e990027..df42011
--- 1/builtin/log.c
--- 2/builtin/log.c
+++ b/builtin/log.c
@@@ -30,8 -30,7 +30,9 @@@
  #include "gpg-interface.h"
  #include "progress.h"
  #include "commit-slab.h"
 +#include "repository.h"
 +#include "commit-reach.h"
+ #include "interdiff.h"
  
  #define MAIL_DEFAULT_WRAP 72
  

diff --cc log-tree.c
Simple merge

diff --cc revision.h
Simple merge