8 bit color still doesn't work, but the -depth command line argument now works properly.
(cherry picked from commit 6765949c27c053d22882f54337cfd09203aa5383)
Leaving xpr unflattened since we want modularity to replace that with xpc (XPluginComposite) at some point
(cherry picked from commit 48e6a75fbdd0fee86e364f02ace83f20b312a2b2)