[show] extra : character in the output of show ip route vrf Vrf1 json

[stepanblyschak]

Description

There is an extra : character in the output of show ip route vrf Vrf1 json, which does not allow to parse it as a json:

admin@sonic:~$ show ip route vrf Vrf1 json | python -m json.tool
Expecting value: line 1 column 1 (char 0)

On the other hand, show ip route json can be successfully parsed as a json.

Steps to reproduce the issue:

1.config vrf add Vrf1
2. show ip route vrf Vrf1 json

Describe the results you received:

admin@sonic:~$ show ip route vrf Vrf1 json
:
{
}

Describe the results you expected:

admin@sonic:~$ show ip route vrf Vrf1 json
{
}

Output of show version:

SONiC Software Version: SONiC.202211_RC1.3-f75df985c_Internal
Distribution: Debian 11.6
Kernel: 5.10.0-18-2-amd64
Build commit: f75df985c
Build date: Mon Jan 16 06:58:56 UTC 2023
Built by: sw-r2d2-bot@r-build-sonic-ci03-244

Platform: x86_64-mlnx_msn3800-r0
HwSKU: Mellanox-SN3800-D112C8
ASIC: mellanox
ASIC Count: 1
Serial Number: MT2208X03840
Model Number: MSN3800-CS2FOS
Hardware Revision: A3
Uptime: 13:45:07 up  3:47,  1 user,  load average: 0.44, 0.73, 0.84
Date: Wed 18 Jan 2023 13:45:07

Docker images:
REPOSITORY                                         TAG                               IMAGE ID       SIZE
docker-platform-monitor                            202211_RC1.3-f75df985c_Internal   044a79ffc9f9   919MB
docker-platform-monitor                            latest                            044a79ffc9f9   919MB
docker-syncd-mlnx                                  202211_RC1.3-f75df985c_Internal   41a58ae1af31   914MB
docker-syncd-mlnx                                  latest                            41a58ae1af31   914MB
docker-orchagent                                   202211_RC1.3-f75df985c_Internal   82223e43ab79   527MB
docker-orchagent                                   latest                            82223e43ab79   527MB
docker-fpm-frr                                     202211_RC1.3-f75df985c_Internal   94715a457670   538MB
docker-fpm-frr                                     latest                            94715a457670   538MB
docker-teamd                                       202211_RC1.3-f75df985c_Internal   ca00cb922564   508MB
docker-teamd                                       latest                            ca00cb922564   508MB
docker-snmp                                        202211_RC1.3-f75df985c_Internal   9a4576a3804e   538MB
docker-snmp                                        latest                            9a4576a3804e   538MB
docker-macsec                                      latest                            b383b7b2b4ff   511MB
docker-dhcp-relay                                  latest                            714676b68a57   502MB
docker-sonic-p4rt                                  202211_RC1.3-f75df985c_Internal   e41876b1d8a6   574MB
docker-sonic-p4rt                                  latest                            e41876b1d8a6   574MB
docker-eventd                                      202211_RC1.3-f75df985c_Internal   4160f1bd9968   492MB
docker-eventd                                      latest                            4160f1bd9968   492MB
docker-sonic-telemetry                             202211_RC1.3-f75df985c_Internal   a3ebba5fcbcc   790MB
docker-sonic-telemetry                             latest                            a3ebba5fcbcc   790MB
docker-lldp                                        202211_RC1.3-f75df985c_Internal   c3dcdddfb4a0   534MB
docker-lldp                                        latest                            c3dcdddfb4a0   534MB
docker-router-advertiser                           202211_RC1.3-f75df985c_Internal   b2ddb1c195e9   492MB
docker-router-advertiser                           latest                            b2ddb1c195e9   492MB
docker-database                                    202211_RC1.3-f75df985c_Internal   48ca7292407a   492MB
docker-database                                    latest                            48ca7292407a   492MB
docker-mux                                         202211_RC1.3-f75df985c_Internal   c89c1002cfa8   541MB
docker-mux                                         latest                            c89c1002cfa8   541MB
docker-sonic-mgmt-framework                        202211_RC1.3-f75df985c_Internal   df629c6e2924   611MB
docker-sonic-mgmt-framework                        latest                            df629c6e2924   611MB
docker-nat                                         202211_RC1.3-f75df985c_Internal   7b748096bbf7   479MB
docker-nat                                         latest                            7b748096bbf7   479MB
docker-sflow                                       202211_RC1.3-f75df985c_Internal   600fd3a28d79   477MB
docker-sflow                                       latest                            600fd3a28d79   477MB
urm.nvidia.com/sw-nbu-sws-sonic-docker/sonic-wjh   1.0.0-master-internal-105         23ddfcb0c5df   327MB
urm.nvidia.com/sw-nbu-sws-sonic-docker/doroce      1.0.0-master-internal-11          9f27047097ac   200MB

Output of show techsupport:

(paste your output here or download and attach the file here )

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

[eddie657]

This bug comes from commit 25acda3 "Fixed SONIC_CLI_IFACE_MODE=alias show ip|ipv6 route output in default mode issue sonic-net/sonic-utilities#2422"
In show/bgp_common.py , it only checks condition if output == "": , however the output is "{}\n" in this test case.