redis-dump -d 6 -k JINJA2_CACHE error

[lguohan]

Description

Steps to reproduce the issue:

1. redis-dump -d 6 -k JINJA2_CACHE

Describe the results you received:

admin@sonic:~$ redis-dump -d 6 -k JINJA2_CACHE
{Traceback (most recent call last):
  File "/usr/local/bin/redis-dump", line 10, in <module>
    sys.exit(main())
  File "/usr/local/lib/python2.7/dist-packages/redisdl.py", line 666, in main
    do_dump(options)
  File "/usr/local/lib/python2.7/dist-packages/redisdl.py", line 587, in do_dump
    dump(output, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/redisdl.py", line 173, in dump
    for key, type, ttl, value in _reader(r, pretty, encoding, keys):
  File "/usr/local/lib/python2.7/dist-packages/redisdl.py", line 283, in _reader
    pretty=pretty, encoding=encoding):
  File "/usr/local/lib/python2.7/dist-packages/redisdl.py", line 341, in _read_keys
    value = reader.handle_response(results[i*3], pretty, encoding)
  File "/usr/local/lib/python2.7/dist-packages/redisdl.py", line 241, in handle_response
    value[k.decode(encoding)] = response[k].decode(encoding)
  File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x80 in position 2: invalid start byte

Describe the results you expected:
it should not have issue.

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

**Output of `show version`:**

admin@str2-7050cx3-acs-03:~$ show version

SONiC Software Version: SONiC.master.436-d03de95e

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

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

[lguohan]

introduced in #3658

[lguohan]

I am not sure if JINJA2_CACHE belongs to state db.

[liat-grozovik]

the cash info is required, the reason for putting it on stat db was just yet another db which is not dumped by the show techsupport. for example: log level or flex counters.
the problem is with redis dump utility so need to move the info to another db which is not used by redis dump.