Auto-Tangents node with spread = 0 and preserve existing = true causes weird change #3822
Description
When spread = 0 and preserve existing = true, we would expect the node to have no effect. But instead, it makes a weird slight change to the geometry based on doing something to the handles as we see here, which goes away when spread becomes slightly larger than 0:
capture_41_.mp4
Paste this into a document:
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