Steps to reproduce:
Change /etc/os-release file with removing double quotes from

PRETTY_NAME="CentOS"

to

PRETTY_NAME=CentOS

So agent will try to get value for key system.sw.os[name] from other file /etc/issue.net
Which could have strange value

# cat /etc/issue.net
\S
Kernel \r on an \m

Which will be reported instead PRETTY_NAME value

Result:

mendeleev ~]# zabbix_get -s 127.1 -k system.sw.os[name]
\S

Expected:

PRETTY_NAME=CentOS
mendeleev ~]# zabbix_get -s 127.1 -k system.sw.os[name]
CentOS

SYSTEM_SW_OS() searches values only inside double-quotes. But VAR=VALUE (with VALUE not enclosed in double-quotes if it doesn't contain white spaces) is also a valid shell syntax and must be supported.