flags.edns_to_text() ignores unknown flags

[pspacek]

Version: 2.8.0

Describe the bug
While using an old version of dnspython to experiment with DELEG protocol, I've noticed flags.edns_to_text() called from message.to_text() ignores unknown EDNS flags.

To Reproduce

import dns.message
print(dns.message.make_query('q', 61440, ednsflags=0x2000))

produces

id 21453
opcode QUERY
rcode NOERROR
flags RD
edns 0
eflags 
payload 1232
;QUESTION
q. IN TYPE61440
;ANSWER
;AUTHORITY
;ADDITIONAL

Note the empty eflags.

I guess most convenient syntax for unknown flags would be their number, something like FLAG3 or EDNSFLAG3, but I do not insist on specific format. Anything which gets the information across works for me.

[rthalley]

This is a fair point and I'll ponder improving this. There is also the "deleg" branch of dnspython which implements draft 7 at the moment (I haven't looked at 8 yet). It supports the flag.