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##### SUMMARY
<!--- Explain the problem briefly below -->
New network modules were added in ansible version 2.9. While testing I came across a bug. More precisely module **ios_l3_interfaces** doesn't set ipv6 addresses correctly when state set to **replaced**. Instead of replacing IP, module just adds it (same behavior as when state is set to merged).

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
ios_l3_interfaces
##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.0
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
Nothing that would affect module logic
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
Host = Debian 9, python 2.7.13
Target = Cisco WS-C4500X-16 Version 03.11.00.E

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->
Before config:
```
interface Vlan100
    ipv6 address 2001:DB8::1/32
    ipv6 enable
```
Ansible playbook example:
```yaml
- name: Configure IPv6
  hosts: cisco4500
  gather_facts: yes
  tasks:
    - ios_l3_interfaces:
        config:
          - name: Vlan100
            ipv6:
              - address: 2001:DB8::2/32
        state: replaced
```

##### EXPECTED RESULTS
I expect module to change IP address from 2001:DB8::1/32 to 2001:DB8::2/32
It works like this for ipv4 (same module) and for ipv4/ipv6 in junos_l3_interfaces.
 
Expected after config:
```
interface Vlan100
    ipv6 address 2001:DB8::2/32
    ipv6 enable
```

##### ACTUAL RESULTS
It merges instead of replaces.

Actual after config:
```
interface Vlan100
    ipv6 address 2001:DB8::1/32
    ipv6 address 2001:DB8::2/32
    ipv6 enable
```

Ansible verbose output:
```
changed: [cisco4500] => {
    "after": [
        {
            "name": "loopback0"
        }, 
        {
            "name": "FastEthernet1"
        }, 
        {
            "name": "TenGigabitEthernet1/1"
        }, 
        {
            "name": "TenGigabitEthernet1/2"
        }, 
        {
            "name": "TenGigabitEthernet1/3"
        }, 
        {
            "name": "TenGigabitEthernet1/4"
        }, 
        {
            "name": "TenGigabitEthernet1/5"
        }, 
        {
            "name": "TenGigabitEthernet1/6"
        }, 
        {
            "name": "TenGigabitEthernet1/7"
        }, 
        {
            "name": "TenGigabitEthernet1/8"
        }, 
        {
            "name": "TenGigabitEthernet1/9"
        }, 
        {
            "name": "TenGigabitEthernet1/10"
        }, 
        {
            "name": "TenGigabitEthernet1/11"
        }, 
        {
            "name": "TenGigabitEthernet1/12"
        }, 
        {
            "name": "TenGigabitEthernet1/13"
        }, 
        {
            "name": "TenGigabitEthernet1/14"
        }, 
        {
            "name": "TenGigabitEthernet1/15"
        }, 
        {
            "name": "TenGigabitEthernet1/16"
        }, 
        {
            "ipv6": [
                {
                    "address": "2001:DB8::1/32"
                }, 
                {
                    "address": "2001:DB8::2/32"
                }
            ], 
            "name": "Vlan100"
        }
    ], 
    "before": [
        {
            "name": "loopback0"
        }, 
        {
            "name": "FastEthernet1"
        }, 
        {
            "name": "TenGigabitEthernet1/1"
        }, 
        {
            "name": "TenGigabitEthernet1/2"
        }, 
        {
            "name": "TenGigabitEthernet1/3"
        }, 
        {
            "name": "TenGigabitEthernet1/4"
        }, 
        {
            "name": "TenGigabitEthernet1/5"
        }, 
        {
            "name": "TenGigabitEthernet1/6"
        }, 
        {
            "name": "TenGigabitEthernet1/7"
        }, 
        {
            "name": "TenGigabitEthernet1/8"
        }, 
        {
            "name": "TenGigabitEthernet1/9"
        }, 
        {
            "name": "TenGigabitEthernet1/10"
        }, 
        {
            "name": "TenGigabitEthernet1/11"
        }, 
        {
            "name": "TenGigabitEthernet1/12"
        }, 
        {
            "name": "TenGigabitEthernet1/13"
        }, 
        {
            "name": "TenGigabitEthernet1/14"
        }, 
        {
            "name": "TenGigabitEthernet1/15"
        }, 
        {
            "name": "TenGigabitEthernet1/16"
        }, 
        {
            "ipv6": [
                {
                    "address": "2001:DB8::1/32"
                }
            ], 
            "name": "Vlan100"
        }
    ], 
    "changed": true, 
    "commands": [
        "interface Vlan100", 
        "ipv6 address 2001:DB8::2/32"
    ], 
    "invocation": {
        "module_args": {
            "config": [
                {
                    "ipv6": [
                        {
                            "address": "2001:DB8::2/32"
                        }
                    ], 
                    "name": "Vlan100"
                }
            ], 
            "state": "replaced"
        }
    }
}
```
if_type = 'FortyGigabitEthernet'
    elif name.lower().startswith('long'):
        if_type = 'LongReachEthernet'
    elif name.lower().startswith('et'):
        if_type = 'Ethernet'
    elif name.lower().startswith('vl'):
        if_type = 'Vlan'
    elif name.lower().startswith('lo'):
        if_type = 'loopback'
    elif name.lower().startswith('po'):
        if_type = 'Port-channel'
    elif name.lower().startswith('nv'):
        if_type = 'nve'
    elif name.lower().startswith('twe'):
        if_type = 'TwentyFiveGigE'
    elif name.lower().startswith('hu'):
        if_type = 'HundredGigE'
    else:
        if_type = None
    number_list = name.split(' ')
    if len(number_list) == 2:
        number = number_list[-1].strip()
    else:
        number = _get_number(name)
    if if_type:
        proper_interface = if_type + number
    else:
        proper_interface = name
    return proper_interface
def get_interface_type(interface):