While existing ejabberd.cfg and ejabberdctl.cfg are preserved, inetrc is overwritten. Each time I make install I have to fix my inetrc which has a critical change in the host tuple. (I have to replace hostalias with the jabber hostname.)
The simple fix is to treat inetrc the same as ejabberd.cfg in Makefile.in:
[ -f $(ETCDIR)/inetrc ] \
&& install -b -m 644 $(G_USER) inetrc $(ETCDIR)/inetrc-new \
|| install -b -m 644 $(G_USER) inetrc $(ETCDIR)/inetrc
Thanks, I've included your fix in the master branch.