I found a fresh chrysalis that was leaking green fluid. The fluid turned black after a while. Research told me that it was blood. I assume a cat had taken a bite out of the C. I moved the C to another container, figuring it would die. It didn't. It turned black on schedule. I happened to catch it right after it eclosed. One of its wings was leaking from a small hole. I find it interesting that in 12 days of development, its body did not fill in the hole -- not even to seal the vessels leading to the hole. Unless somehow the wing was pinched by the C shell and the hole was created when the B eclosed.
The day after I found the first leaking C, I found another one. Removed it. It also eclosed normally, but had a gimpy leg -- either permanently folded or missing a segment.
Anyway, one lesson learned is: don't give up on leaking C's.