This is new to 15w37a – do not exist in prior snapshots or Minecraft versions.
Expected: Vines below the removed vine stay on tree stem (or other block).
Happened: All vines below and connected to the removed vine is automatically deleted. (So the vines now growing ON the stem acts like free floating vines.)
I've read through all vine-related bug reports without finding this one.
Is this a new feature or a bug?
PROBABLY RELATED to the Vines can't be placed-bug.