Boolean flag completion doesn't work

[rtweeks]

Flags like --[no-]log display in the completion list when the incomplete argument is --, but when the incomplete argument contains either a part of no or the positive flag, the Boolean flag is not offered in the completions. This table might explain it better:

Incomplete Argument	Completions Offered	Should Be Offering
--	--log --no-log	✅ --log --no-log
--n	none	❌ --no-log
--l	none	❌ --log