Issue of upgrading from 9.0.4 to 9.1.3

Hi All,

We used 9.0.4 before and recently we plan to upgrade to 9.1.3. During
the test, we found a issue related to escape letter as below:

in 9.0.4, the sql is correct
insert into test values('abc\'a');

but in 9.1.3, the postgresql denied the same sql, then it worked after
I changed it to
insert into test values('abc''a');

How to configure 9.1.3 and let it also accept \ as the escpage? Could
someone help me out?

thanks very much.