I have always been a firm believer in anything with brakes, replace it, I would tighten the nuts up then clean it up 100%, have someone pump the brakes a few times with the engine running to get the boast & check the leak, this will tell you where the leak is, if it is in the brake line replace both front lines, keep the good one as an emergency spare, just some thought, when undoing breaklines jamb a golf TEE in the hole, you may need to whittle it to a tapered point, the wood will squash a little to hold out the air long enough for you to change the line, this stops lots of air in the line & much much easier to bleed the small pocket of air out off the brakes afterwards, often good enough to bleed that line only & get away with it, done it many many times.
The reason I do both sides is I believe if one side has failed the other could fail, do both sides & keep the good spare, you have double peace of mind, one it is all done nicely & second you have something that will get you home in an imergency, always keep a golf tee in your kit, takes no room