The newly added header file seems to be missing after installation, this makes network-multicast-0.2.0 fail to build:
Configuring network-multicast-0.2.0...
Preprocessing library for network-multicast-0.2.0..
In file included from Multicast.hsc:15:
/usr/lib/ghc-8.4.3/site-local/network-2.7.0.1/include/HsNet.h:10:10: fatal error: HsNetDef.h: No such file or directory
#include "HsNetDef.h"
^~~~~~~~~~~~
compilation terminated.