8b6ce77f16
In 8d1978a8e0 bmain entry is updated when prefetching is started,
but this must be done before seq_prefetch_update_context(). Otherwise
created cache keys will be incorrect.
This happens immediately after prefetch is started. When it's refreshed
problem goes away.
Reviewed By: sergey
Differential Revision: https://developer.blender.org/D9581