Description:
------------
When remote SNMP agent returns an error with same OID that contained correct value *_real_walk functions will overwrite this correct value with error message because there is no snmp reply status check.

Here is patch to address this issue:
========
--- ext/snmp/snmp.c.orig        2008-12-31 14:17:43.000000000 +0300
+++ ext/snmp/snmp.c     2009-05-14 10:31:23.000000000 +0400
@@ -480,12 +480,15 @@
                                        } else if (st == SNMP_CMD_WALK) {
                                                add_next_index_zval(return_value,snmpval); /* Add to returned array */
                                        } else if (st == SNMP_CMD_REALWALK)  {
+                                               if (vars->type != SNMP_ENDOFMIBVIEW &&
+                                                       vars->type != SNMP_NOSUCHOBJECT && vars->type != SNMP_NOSUCHINSTANCE) {
 #ifdef HAVE_NET_SNMP
-                                               snprint_objid(buf2, sizeof(buf2), vars->name, vars->name_length);
+                                                       snprint_objid(buf2, sizeof(buf2), vars->name, vars->name_length);
 #else
-                                               sprint_objid(buf2, vars->name, vars->name_length);
+                                                       sprint_objid(buf2, vars->name, vars->name_length);
 #endif
-                                               add_assoc_zval(return_value,buf2,snmpval);
+                                                       add_assoc_zval(return_value,buf2,snmpval);
+                                               }
                                        }
                                        if (st >= SNMP_CMD_WALK && st != SNMP_CMD_SET) {
                                                if (vars->type != SNMP_ENDOFMIBVIEW &&
============

in BASE64 form:
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IFNOTVBfRU5ET0ZNSUJWSUVXICYmIAo=
====


Reproduce code:
---------------
print_r(@snmp2_real_walk("host:161", "community", ".1.3.6.1.4.1.8072.2.1.2.3", (800 * 1000), 2)):
=======
Result shown by snmpwalk:
>snmpwalk -v2c -ccommunity host .1.3.6.1.4.1.8072.2.1.2.3
NET-SNMP-MIB::netSnmp.2.1.2.3.1 = ""
NET-SNMP-MIB::netSnmp.2.1.2.3.2 = ""
NET-SNMP-MIB::netSnmp.2.1.2.3.3 = ""
NET-SNMP-MIB::netSnmp.2.1.2.3.4 = ""
NET-SNMP-MIB::netSnmp.2.1.2.3.5 = ""
NET-SNMP-MIB::netSnmp.2.1.2.3.6 = ""
NET-SNMP-MIB::netSnmp.2.1.2.3.7 = ""
NET-SNMP-MIB::netSnmp.2.1.2.3.8 = STRING: "blah"
NET-SNMP-MIB::netSnmp.2.1.2.3.8 = No more variables left in this MIB View (It is past the end of the MIB tree)


Expected result:
----------------
Array
(
    [NET-SNMP-MIB::netSnmp.2.1.2.3.1] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.2] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.3] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.4] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.5] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.6] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.7] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.8] => "blah"
)

Actual result:
--------------
Array
(
    [NET-SNMP-MIB::netSnmp.2.1.2.3.1] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.2] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.3] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.4] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.5] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.6] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.7] => ""
    [NET-SNMP-MIB::netSnmp.2.1.2.3.8] => No Such Instance currently exists at this OID
)