Meta-sink operations shouldn't need to implement prepare() and process()
Submitted by Daniel Sabo
Link to original bug (#720300)
Description
The graph traversal works by following the graph connections and rendering every relevant Node object. When given a meta-sink operation it sees the meta-noop as the final node to be processed and follows it's input pads to find the relevant nodes. This means that for an operation like gegl:save it will never call process() on the actual save operation, instead the gegl:save operation manually proxies the process call to the real save node. It also means that it is impossible for a meta-sink node to contain more than a single node, because the graph traversal can't see any nodes before the meta-noop's "output" pad.
Version: git master