row_search_for_mysql() is called without ha_innobase::external_lock()

Just wondering if somebody came across an issue in Percona 5.1.{54,56,57,58} for rhel5 x86_64 where a lot of error messages generated to .err file but the query itself works fine.
{code}
row_search_for_mysql() is called without ha_innobase::external_lock()
{code}

I don’t remember seeing that error message in any version of MySQL, ever. Is it reproducible on stock MySQL?

There is no stock MySQL 5.1 in CentOS 5 or epel repos.
However, we could not reproduce it in MacOS or Gentoo versions (both 5.1.56).