patch 7.4.1552
Problem:    ":colorscheme" does not use 'packpath'.
Solution:   Also use in "start" and "opt" directories in 'packpath'.
diff --git a/src/if_py_both.h b/src/if_py_both.h
index 6ae3fe7..e916e6a 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -1061,7 +1061,7 @@
     data.callable = callable;
     data.result = NULL;
 
-    do_in_runtimepath(NULL, FALSE, &map_rtp_callback, &data);
+    do_in_runtimepath(NULL, 0, &map_rtp_callback, &data);
 
     if (data.result == NULL)
     {
@@ -1150,7 +1150,7 @@
     if (!(ret = PyList_New(0)))
 	return NULL;
 
-    do_in_runtimepath(NULL, FALSE, &map_finder_callback, ret);
+    do_in_runtimepath(NULL, 0, &map_finder_callback, ret);
 
     if (PyErr_Occurred())
     {