Fixed by upstream frr 9.1 release. There was a missing exit when entering frr-reload contexts.

Do not see the difference with 1.3.6

$ ./automation.sh te123
++ dirname ./automation.sh
+ SCRIPT_DIR=.
+ HOST=te123
+ echo 'local arg of host: te123'
local arg of host: te123
+ ssh [email protected] '/bin/vbash -s' te123
remote hostname: 1

It is not a bug for 1.5/1.4

set policy route-map FOO rule 10 action 'permit'
set policy route-map FOOv6 rule 10 action 'permit'

Marked this as resolved since the fix was merged and backported.

Moving to systemd-networkd on the long run seems like a very nice idea that I also had. For no and the 1.4 LTS release we will stick with a custom isc-dhcp-client package build

The examples in T5939 reveal a general issue that, although uncommon, needs to be rationalized. The modern parser requires single backslashes to be escaped, if in quoted strings, however (1) the legacy parser (unlike the modern parser) is inconsistent in quoting values (2) the existing solution escapes all single backslashes not a part of control sequences and makes no attempt to restore single backslashes when possible --- this is safe, but leads to redundant escaping of backslashes as revealed in the examples in T5939.