extract_json_value fails with negative value

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Which version of common_schema are you using? (specify
revision+distribution)
2.2 523
Which component is failing? (specify the view, function, etc.)
select extract_json_value('{"test":"-2"}','/test'); fails returning NULL
but remove the negative and the function works.
select extract_json_value('{"test":"2"}','/test');

What is the expected output? What do you see instead?
Expect to see 2 instead of NULL

Can you provide with sample data?

(As of version 1.1), please provide output of
SELECT * FROM common_schema.status

Please provide any additional information below.
I do not have the entire common_schema installed as I don't have permission in 
my VPS but I have installed the following functions/procedures
get_json_token
encode_xml
extract_json_value
json_to_xml
trim_wspace
unquote

Original issue reported on code.google.com by [email protected] on 29 Nov 2013 at 2:47