Merge branch 'mk/show-s-no-extra-blank-line-for-merges' into maint

"git show -s" (i.e. show log message only) used to incorrectly emit
an extra blank line after a merge commit.

* mk/show-s-no-extra-blank-line-for-merges:
  git-show: fix 'git show -s' to not add extra terminator after merge commit

combine-diff.c

@@ -1339,7 +1339,8 @@ void diff_tree_combined(const unsigned char *sha1,
 		if (show_log_first && i == 0) {
 			show_log(rev);
 
-			if (rev->verbose_header && opt->output_format)
+			if (rev->verbose_header && opt->output_format &&
+			    opt->output_format != DIFF_FORMAT_NO_OUTPUT)
 				printf("%s%c", diff_line_prefix(opt),
 				       opt->line_termination);
 		}