Description

Steps to reproduce the issue:

1. load config_db.json which has this in PORT section:
   PORT: {
   "Ethernet112": {
   "alias": "Eth29/1",
   "lanes": "113,114",
   "speed": "50000",
   "index": "28"
   },
   ....
   }

sudo config interface Ethernet112 startup

3. sonic-cfggen -d --print-data
   PORT: {
   "Ethernet112": {
   "admin_status": "up"
   },
   ..
   }

This will break any other subsequence commands like "show version"

File "/usr/bin/show", line 9, in
load_entry_point('sonic-utilities==1.2', 'console_scripts', 'show')()
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 561, in load_entry_point
return get_distribution(dist).load_entry_point(group, name)
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 2631, in load_entry_point
return ep.load()
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 2291, in load
return self.resolve()
File "/usr/lib/python2.7/dist-packages/pkg_resources/init.py", line 2297, in resolve
module = import(self.module_name, fromlist=['name'], level=0)
File "/usr/lib/python2.7/dist-packages/show/main.py", line 193, in
iface_alias_converter = InterfaceAliasConverter()
File "/usr/lib/python2.7/dist-packages/show/main.py", line 58, in init
self.port_dict[port_name]['alias']):
KeyError: 'alias'

Describe the results you received:

Describe the results you expected:

Additional information you deem important (e.g. issue happens only occasionally):

**Output of `show version`:**
914d5c74519418a4f9430493b169d36c4474c75d

```
(paste your output here)
```

**Attach debug file `sudo generate_dump`:**

```
(paste your output here)
```