Description:
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Unicode character properties doesn't work in preg_replace (since PHP 5.2.7).

PCRE (Perl Compatible Regular Expressions) Support 	enabled
PCRE Library Version: 7.8 2008-09-05 


Results with phpinfo: http://seo-servis.cz/testpl.php

Reproduce code:
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echo preg_replace("~[^\\pL]+~u", '-', "a 3");

echo preg_replace('~[^\\p{L}]+~u', '-', "a 3");

Expected result:
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a-3
a-3

Actual result:
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Warning: preg_replace() [function.preg-replace]: Compilation failed: unknown property name after \P or \p at offset 4 in xxx on line 3

Warning: preg_replace() [function.preg-replace]: Compilation failed: unknown property name after \P or \p at offset 6 in xxx on line 4