Seems to be marked broken due to 'does not fetch'. At least http://distfiles.macports.org/libproplist/libPropList-0.10.1.tar.gz still has a copy. Would be good to keep it alive for now.
A commit references this bug: Author: pi Date: Tue Apr 5 17:47:29 UTC 2016 New revision: 412577 URL: https://svnweb.freebsd.org/changeset/ports/412577 Log: devel/libPropList: new distsite, unbreak PR: 208549 Submitted by: bz Changes: head/devel/libPropList/Makefile
Committed, thanks.