This excellent answer to the question Why has no TLE been published for the DSCOVR satellite and the Falcon 9 R/B? suggests that to the best of the writer's knowledge TLEs are only issued for spacecraft in Earth orbit, presumably meaning a gravitationally bound orbit (rather than a hyperbolic one).
However, I'm thinking that it is certainly conceivable that one might be issued for a spacecraft executing a flyby maneuver of Earth if it is low enough and could potentially interact with other satellites as a precaution.
Then again, I'm thinking that this might be useless/meaningless since the format of a TLE requires a value for mean motion (revolutions/day) and there is no way the other parameters have enough information to describe an orbit without some way to communicate the semi-major axis, which would be negative for a hyperbolic fly-by.
Since Two-Line Element sets actually contain a blank space at column 52 (see Wikipedia and Celestrak) where a minus sign could potentially be inserted, in some universe it might be possible to actually do this. Also, Three-Line Element sets are at least defined (see Celestrak PDF) though I am not sure how often they are used, and columns 11 and 12 of card 3 are explicitly labeled "orbit type".
Question: So I'd like to know if a Two-Line or Three-Line Element set has ever been issued for a spacecraft trajectory not bound to Earth orbit, or if in fact none have, then in that case if one could be issued if necessary. Looking for a well-supported, factual answer, not just a "not to my knowledge" response.