RBM wrote:
....

--I agree that clearly marking the ends of the wire are a better than
nothing solution, but as the OP said, there must be at least one other
junction box where this wire exists. It's one thing to see a green wire
attached to a breaker or the hot side of a receptacle, but it's another
thing to have a green wire in a junction box, with nothing to define that
it's hot. I wouldn't be concerned about any "electrician" mistaking it, as
electricians would tend to be more careful regarding wires they are
connecting to, but an amateur may easily believe that it is a ground, and
in an awkward location like a tight attic, get himself hurt. This is
probably why the NEC prohibits remarking a green conductor

Certainly, but...it's already there and been there for some years.

I'm not anal-enough to rip it out just because some previous doofus ran
a green wire when shoulda' pulled a
black/red/anything_but_white_or_green one...

Again, this is based on the previous qualification OP has correctly
identified the situation and the conductor is continuous on the neutral
from the breaker to the other end and is _NOT_ also a ground doubling as
a neutral but is merely a misuse of green-insulated wire as a neutral.

If one of the other faults is also present then it definitely ought to
be corrected.

--