Why there is a difference between 6.3 and 6.4 regarding auto negotiation for Fibre

Issue

• Why the ethtool behaviour in 6.3 is not proper?
• What are the changes made in 6.4 compared with 6.3?
• In RHEL6.3, ethtool shows,
  • Supports auto-negotiation is No.
  • Advertised auto-negotiation is No.
  • Auto-negotiation is on.

$ ethtool eth0
Settings for eth0:
        Supported ports: [ FIBRE ]
        Supported link modes:   1000baseT/Full
                                10000baseT/Full
        Supports auto-negotiation: No
        Advertised link modes:  1000baseT/Full
                                10000baseT/Full
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Speed: 10000Mb/s
        Duplex: Full
        Port: Other
        PHYAD: 0
        Transceiver: external
        Auto-negotiation: on
        Supports Wake-on: umbg
        Wake-on: g
        Current message level: 0x00000007 (7)
        Link detected: yes

• But when I try the same thing on RHEL 6.4,
  • Supports auto-negotiation is Yes
  • Advertised auto-negotiation is Yes
  • Auto-negotiation is on

$ ethtool eth0
Settings for eth0:
        Supported ports: [ FIBRE ]
        Supported link modes:   1000baseT/Full
                                10000baseT/Full
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Advertised link modes:  1000baseT/Full
                                10000baseT/Full
        Advertised pause frame use: No
        Advertised auto-negotiation: Yes
        Speed: 10000Mb/s
        Duplex: Full
        Port: Other
        PHYAD: 0
        Transceiver: external
        Auto-negotiation: on
        Supports Wake-on: umbg
        Wake-on: g
        Current message level: 0x00000007 (7)
                               drv probe link
        Link detected: yes