[exim-dev] quote_pgsql and PostgreSQL 9.1.2

After upgrading to pgsql 9.1.2 from 8.4, I'm getting:

    test\_underscore
from
    '${quote_pgsql:${lc:$sender_address_local_part}}'
where sender_address_local_part is
    test_underscore
Quote from
    9.21 More about MySQL, PostgreSQL, Oracle, and InterBase:
"The quote_pgsql expansion operator, in addition, escapes the percent and underscore characters."
Why do we take percent and underscore special?
Is this a bug?

Axel
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