Cycles preview rendering could free the image buffers being used by drawing in
another thread due to a race condition. This race condition was unlikely before,
but now that preview renders are started right before we draw the image in the
image editor or load it as a texture in the 3D viewport, it's likely to happen.
As we are close to release this is too risky to fix properly, just avoid freeing
the cache for preview renders instead and accept increased memory usage in some
cases.
Remove prefix of filenames that is the same as the folder name. This used
to help when #includes were using individual files, but now they are always
relative to the cycles root directory and so the prefixes are redundant.
For patches and branches, git merge and rebase should be able to detect the
renames and move over code to the right file.
