Bug in parser

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Andriy I Pilipenko
Your email address : bamby(at)marka(dot)net(dot)ua

System Configuration
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Architecture (example: Intel Pentium) : i486 and higher

Operating System (example: Linux 2.0.26 ELF) : FreeBSD 2.2.6
FreeBSD 2.2.7
Linux 2.0.34 ELF

PostgreSQL version (example: PostgreSQL-6.4.2) : PostgreSQL-6.4
PostgreSQL-6.4.2

Compiler used (example: gcc 2.8.0) : gcc 2.7.2.1

Please enter a FULL description of your problem:
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Backend reports syntax error near unary '-' in queries like:

SELECT * FROM some_table WHERE some_column IN ( <negative number> )
^^^^^^^^^^^^^^^^^^^^^^^^
This bug not existed in 6.3.2. It first appeared in 6.4 and remains in
6.4.2.

Please describe a way to repeat the problem. Please try to provide a
concise reproducible example, if at all possible:
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Bug is very easy to reproduce. See query above.

If you know how this problem might be fixed, list the solution below:
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