Merge branch 'jk/bisect-show-tree' into maint

"git bisect" makes an internal call to "git diff-tree" when
bisection finds the culprit, but this call did not initialize the
data structure to pass to the diff-tree API correctly.

* jk/bisect-show-tree:
  bisect: always call setup_revisions after init_revisions

bisect.c

@@ -890,6 +890,7 @@ static void show_diff_tree(const char *prefix, struct commit *commit)
 	if (!opt.diffopt.output_format)
 		opt.diffopt.output_format = DIFF_FORMAT_RAW;
 
+	setup_revisions(0, NULL, &opt, NULL);
 	log_tree_commit(&opt, commit);
 }