Comment 12 for bug 1699484

One final observation before EOD:

if I hack mgn::NestedBufferPlatform::create_buffer_allocator() to only ever use rendering_platform->create_buffer_allocator(); then on starting an EGL client the server immediately hits the "intel_do_flush_locked failed: No such file or directory" error.

So I suspect that the mgm::BufferAllocator simply doesn't work in this configuration.