yaml parsing is wrong when key's value has leading colon

[subeditara]

replication steps:

ruby -ryaml -e "a = YAML.load('servers: ::ffff:10.10.10.1'); puts a; puts a['servers']"
{"servers"=>:":ffff:10.10.10.1"}
:ffff:10.10.10.1

expected:

{"servers"=>"::ffff:10.10.10.1"}
::ffff:10.10.10.1

actual result:

{"servers"=>:":ffff:10.10.10.1"}
:ffff:10.10.10.1

Environment:

ruby --version
ruby 2.7.0p0

gem list yaml 
yaml (0.3.0)

Python yaml works as expected:

python3.9 -c 'import yaml; a=yaml.safe_load("servers: ::ffff:10.10.10.1"); print(a); print(a["servers"]);'
{'servers': '::ffff:10.10.10.1'}
::ffff:10.10.10.1

[tenderlove]

I guess this is because Python doesn't have the concept of a Symbol like Ruby does?

As a work-around, this should work (untested):

ruby -ryaml -e "a = YAML.load('servers: "::ffff:10.10.10.1"'); puts a; puts a['servers']"

I'm not sure what to do about this. I'm sure there are Ruby users that well expect symbols in this case so I don't want to change the behavior.