Blender now calls render hooks before taking copy of `scene->r` in
`RE_RenderAnim()`.
A change to the render output filename made in the render-init hook
would not be picked up by by the copy. As a result, placeholders were
touched using the old name, whereas the rendered images would be saved
with the new filename.
Reviewers: sergey
Maniphest Tasks: T66555
Differential Revision: https://developer.blender.org/D5887
f94f4e1d79