**Steps to reproduce:**
- Start Blender with default scene, set renderer to Cycles
- Enable vector pass
- Enable motion blur
- Render
- Render again
**Expected result**
Both renders should not contain a vector pass.
**Actual result**
The first render contains a vector pass, the second doesn't.
**Notes**
`blender_sync.cpp` is doing things in the wrong order. `BlenderSync::sync_render_passes()` checks the `scene->integrator->motion_blur` flag, but that gets synced later.