Merge branch 'jk/diff-follow-must-take-one-pathspec' into maint

"git format-patch" did not enforce the rule that the "--follow"
option from the log/diff family of commands must be used with
exactly one pathspec.

* jk/diff-follow-must-take-one-pathspec:
  move "--follow needs one pathspec" rule to diff_setup_done

diff --cc builtin/log.c
Simple merge

diff --cc diff.c
index f72769a1c492dfcac501032c54c3fb2ac0a4343e,a99b925ac74bc4f513bd9d860e757f385cca871b..68bb8c5a8493500b127ccac7327133d09acdcdcb
--- 1/diff.c
--- 2/diff.c
+++ b/diff.c
@@@ -3324,7 -3318,8 +3324,10 @@@ void diff_setup_done(struct diff_option
                DIFF_OPT_SET(options, EXIT_WITH_STATUS);
        }
  
 +      options->diff_path_counter = 0;
++
+       if (DIFF_OPT_TST(options, FOLLOW_RENAMES) && options->pathspec.nr != 1)
+               die(_("--follow requires exactly one pathspec"));
  }
  
  static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)