Not a common scenario, but if you had very few source images (e.g.
long image strips with one frame) and many final frames cached,
the full cache eviction policy was not handling that well, since it
was always removing at least one source image for each final frame.
Resulting in effectively the cache only being full of final frames.
Change that so:
1) evict_caches_if_full has a loop that tries to evict until the caches
are not full (i.e. not necessarily just one image), and
2) only evict source image per final frame, if there are more source
images cached.
Pull Request: https://projects.blender.org/blender/blender/pulls/144612
e8f1c6ee4d