race condition in pgplsql call handler?

I'm looking into PG/PLSql code and following code in 
plpgsql_call_handler looks strange:
        /* Find or compile the function */        func = plpgsql_compile(fcinfo, false);
        /* Mark the function as busy, so it can't be deleted from under 
us */        func->use_count++;


I don't have deep knowledge about this part of code. But what happen if 
in parallel execution "func" will be deleted between these two lines?

    Zdenek