sshd_config lens: Not possible to create or remove subsystem

[minfrin]

Using v1.13.0, given the following set of subsystems:

blackadder ~ # /usr/bin/augtool --echo --load-file=/etc/ssh/sshd_config
augtool> print /files/etc/ssh/sshd_config/Subsystem
/files/etc/ssh/sshd_config/Subsystem[1]
/files/etc/ssh/sshd_config/Subsystem[1]/sftp = "/usr/libexec/openssh/sftp-server"
/files/etc/ssh/sshd_config/Subsystem[2]
/files/etc/ssh/sshd_config/Subsystem[2]/snmp = "/usr/bin/sshtosnmp /var/lib/net-snmp/sshdomainsocket"

It is not possible to add a new subsystem:

augtool> set /files/etc/ssh/sshd_config/Subsystem/foo "something new"
error: Too many matches for path expression

It is not possible to remove an existing subsystem:

augtool> rm /files/etc/ssh/sshd_config/Subsystem/snmp
rm : /files/etc/ssh/sshd_config/Subsystem/snmp 1
augtool> save
error: Failed to execute command
saving failed (run 'errors' for details)

Updating subsystems works fine.

augtool> set /files/etc/ssh/sshd_config/Subsystem/snmp "something else"
augtool> print /files/etc/ssh/sshd_config/Subsystem
/files/etc/ssh/sshd_config/Subsystem[1]
/files/etc/ssh/sshd_config/Subsystem[1]/sftp = "/usr/libexec/openssh/sftp-server"
/files/etc/ssh/sshd_config/Subsystem[2]
/files/etc/ssh/sshd_config/Subsystem[2]/snmp = "something else"