npgsql - Npgsql2: Fixed previous patch as it breaks when using an

Log Message:
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Fixed previous patch as it breaks when using an internal NpgsqlCommand which receives only a Connector in its
constructoras the CheckConformingStrings method does. This is caused by not having an NpgsqlConnection available when
usingthis internal constructor. Now it uses the Connector object instead of NpgsqlConnection to get the compatibility
versioncheck. 

Modified Files:
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    Npgsql2/src/Npgsql:
        NpgsqlDataReader.cs (r1.20 -> r1.21)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/npgsql/Npgsql2/src/Npgsql/NpgsqlDataReader.cs?r1=1.20&r2=1.21)