The loading of prc files is not that magical. It looks in various directories, but doesn’t make up a completely new filename. The loading of the display modules is even less magic–it doesn’t even look in various directories for that one.
So, that filename isn’t being requested by any Panda code. It must be loaded indirectly by the dylibs that libpandagl pulls in, which is to say, by your OpenGL drivers. You can test this by calling dlopen(‘libpandagl.dylib’) or even dlopen(‘libGL.dylib’) (or whatever your OpenGL library is called) in a sample program.
David