Merge branch 'xy/format-patch-prereq-patch-id-fix'

Recently added "--base" option to "git format-patch" command did
not correctly generate prereq patch ids.

* xy/format-patch-prereq-patch-id-fix:
  format-patch: clear UNINTERESTING flag before prepare_bases

builtin/log.c

@@ -1756,6 +1756,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	if (base_commit || base_auto) {
 		struct commit *base = get_base_commit(base_commit, list, nr);
 		reset_revision_walk();
+		clear_object_flags(UNINTERESTING);
 		prepare_bases(&bases, base, list, nr);
 	}