From: t-ishii@sra.co.jp

As mentioned around line 1153 in backend/commands/copy.c, the method
of array checking is not perfect.

test=> create table t1 (i text);
test=> insert into t1 values('{\\.}');
INSERT 2645600 1
test=> select * from t1;
i
-----
{\\.}
(2 rows)
test=> copy t1 to '/tmp/aaa';
test=> copy t1 from '/tmp/aaa';
ERROR:  CopyReadAttribute - end of record marker corrupted

Copy cannot read data produced by itself!