Blender Git Loki

Fix first part of T86501: Crash during resync process.

Code would end up freeing some of the newly created overrides, which
were assigned to the matching linked ID's `newid` pointer, accessed
again further down the code.

Note that this is not a normal expected situation, and it won't give a
proper resync result anyway, but it might happen in some complicated
corner cases, and also quite often when dealing with older .blend files.