tmt test import got "list index out of range" when restraint metadata includes empty attributes

[smyle10]

tmt-1.35.0-1

Given a metadata file:

[General]
name=/kernel/networking/netfilter/modules_params
description=/kernel/networking/netfilter/modules_params
license=GPLv2
confidential=no
destructive=no

[restraint]
entry_point=bash ./runtest.sh
max_time=2h
softDependencies=    # <-------------------------- empty here
repoRequires=networking/common

tmt test import --restraint got:

$ tmt -vvvvdddd test import --restraint -vvvvdddd
Checking the '/home/mshi/wks/kernel/networking/netfilter/modules_params' directory.
Restraint file found in '/home/mshi/wks/kernel/networking/netfilter/modules_params/metadata'.
task: /kernel/networking/netfilter/modules_params
summary: /kernel/networking/netfilter/modules_params
test: bash ./runtest.sh
framework: shell
duration: 2h
recommend:
Purpose found in '/home/mshi/wks/kernel/networking/netfilter/modules_params/PURPOSE'.
description:
This testcase aim to test netfilter modules:
1.loadable/unload
2.doubled params load #bz1601662
3,fuzzed params load
Nitrate No non-disabled testcase found for '/kernel/networking/netfilter/modules_params'.

list index out of range

Removing the line "softDependencies=" makes it work