note 98750 deleted from function.preg-replace-callback by danbrown

Note Submitter: Min Thu Kyaw ---- <<preg_replace_callback returns NULL when pcre.backtrack_limit is reached; this sometimes occurs faster then you might expect. No error is raised either; so don't forget to check for NULL yourself>> It is useful note for me . thank for that . It made me fool around to figure out what my coding going wrong .if backtrack reach its limit ,It wont write info out .