While trying to compile old code, I run into the error:

node.cpp:13:31: fatal error: opencv2/imgproc.hpp: No such file or directory
 #include <opencv2/imgproc.hpp>

If I change the include line in the code to

#include <opencv2/imgproc/imgproc.hpp>

then it compiles fine.

Is there something that has changed in my environment? How do I get the first version to compile consistently?