[exim] Bug in string expansion of exim configuration?

Hello exim developers,

must i write to the exim-dev mailing list?

I am running a mailsystem on Debian jessie with Exim version 4.84_2 #1 built 25-Jul-2016.

In my configuration i am trying to use some values fetching from an mysql database.
This is working in the router section for identifying the users without problem.

But when i try get the values for spam it fails!


Here this configuration:

That's what is working now - but it is not per user
       condition = ${if >{$spam_score_int}{50}{1}{0}}

That's what i want to do:

       condition = ${if >{$spam_score_int}{${eval:10*{${lookup mysql{ SELECT DISTINCT spam_threshold FROM user WHERE
username='${quote_mysql:$local_part}' AND domain='${quote_mysql:$domain}' AND SMTP_allowed='YES'}}}}}{true}{false}}

This will result in:

temporarily rejected after DATA: failed to expand ACL string
"${if >{$spam_score_int}{${eval:10*{${lookup mysql{ SELECT DISTINCT spam_threshold FROM user WHERE
username='${quote_mysql:$local_part}' AND domain='${quote_mysql:$domain}' AND SMTP_allowed='YES'}}}}}{true}{false}}":
error in expression evaluation: expecting number or opening parenthesis (after processing "10*")


>From my point of view the syntax is correct.
Can you help me to see the error?

Thanks a lot.