Thanks to 
https://www.mail-archive.com/libguestfs@redhat.com/msg13973.html

--- a/actions.h	2018-02-28 00:39:13.189935224 -0500
+++ b/actions.h	2018-02-28 00:40:33.010503002 -0500
@@ -57,9 +57,6 @@
 {
   assert (g);
 #ifndef HAVE_PYCAPSULE_NEW
-  return
-    PyCObject_FromVoidPtrAndDesc ((void *) g, (char *) "guestfs_h", NULL);
-#else
   return PyCapsule_New ((void *) g, "guestfs_h", NULL);
 #endif
 }