[c-nsp] IOS 15.0 ipv6-related weirdness (fails to fallback to ipv4)

[Michael Ulitskiy]

Hello,

I have a 2800 router with IOS 15.0(1)M7 with no ipv6 connectivity. There are no ipv6
addresses configured on any interfaces and i've added:

no ipv6 cef
no ipv6 unicast-routing

commands to config.

Nonetheless when I try to ping google the following happens:

c2800#ping google.com
Translating "google.com"...domain server (167.206.112.138) [OK]

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2607:F8B0:4006:801::1004, timeout is 2 seconds:

% No valid source address for destination
Success rate is 0 percent (0/1)

c2800#sh hosts 
Default domain is aceinnovative.com
Name/address lookup uses domain service
Name servers are 167.206.112.138, 167.206.7.4

Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
       temp - temporary, perm - permanent
       NA - Not Applicable None - Not defined

Host                      Port  Flags      Age Type   Address(es)
google.com                None  (temp, OK)  0  IPv6   2607:F8B0:4006:801::1004

So when it sees AAAA record it tries to use it (regardless ipv6 routing has been disabled), sees 
there're no valid ipv6 addresses to use as source and fails, instead of trying to use alternative
ipv4 addresses. It's also very strange that only IPv6 address has been cached by resolver.
It looks like resolver discards any A record in the presence of AAAA.

FYI:
c2800#sh ipv6 interface brief 
FastEthernet0/0            [up/up]
    unassigned
FastEthernet0/1            [up/up]
    unassigned

c2800#sh ipv6 route
IPv6 Routing Table - default - 1 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
       I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
       D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
L   FF00::/8 [0/0]
     via Null0, receive

I wonder if this is a known issue, if there are any workarounds or if I'm missing something?
Thank you,

Michael Ulitskiy