Fix #20 and added an ATF test-case.

tests/xbps/libxbps/Makefile

@@ -11,5 +11,6 @@ SUBDIRS += find_pkg_obsoletes
 SUBDIRS += find_pkg_orphans
 SUBDIRS += pkgdb
 SUBDIRS += issue18
+SUBDIRS += issue20
 
 include ../../../mk/subdir.mk

tests/xbps/libxbps/common/Kyuafile

@@ -9,5 +9,6 @@ atf_test_program{name="plist_match_test"}
 atf_test_program{name="plist_match_virtual_test"}
 atf_test_program{name="find_pkg_obsoletes_test"}
 atf_test_program{name="issue18_test"}
+atf_test_program{name="issue20_test"}
 include('find_pkg_orphans/Kyuafile')
 include('pkgdb/Kyuafile')

tests/xbps/libxbps/issue20/Makefile

@@ -0,0 +1,7 @@
+TOPDIR = ../../../..
+-include $(TOPDIR)/config.mk
+
+TEST = issue20_test
+
+include ../Makefile.inc
+include $(TOPDIR)/mk/test-shell.mk

tests/xbps/libxbps/issue20/issue20_test.sh

@@ -0,0 +1,57 @@
+#! /usr/bin/env atf-sh
+
+# xbps issue #20.
+# How to reproduce it:
+#	Create pkg a-0.1_1 containing 1 file and 1 symlink:
+#
+#		/foo
+#		/blah -> foo
+#
+#	Create pkg a-0.2_1 containing 1 file and 1 symlink (inverted):
+#
+#		/foo -> blah
+#		/blah
+#
+#	Upgrade pkg a to 0.2.
+
+atf_test_case issue20
+
+issue20_head() {
+	atf_set "descr" "xbps issue #20 (https://github.com/xtraeme/xbps/issues/18)"
+}
+
+issue20_body() {
+	mkdir repo
+	cd repo
+	mkdir pkg_a
+	touch pkg_a/foo
+	ln -sr pkg_a/foo pkg_a/blah
+	xbps-create -A noarch -n a-0.1_1 -s "pkg a" pkg_a
+	atf_check_equal $? 0
+	rm -rf pkg_a
+	xbps-rindex -a *.xbps
+	atf_check_equal $? 0
+	xbps-install -r rootdir --repository=$PWD -y a
+	atf_check_equal $? 0
+
+	mkdir pkg_a
+	touch pkg_a/blah
+	ln -sr pkg_a/blah pkg_a/foo
+	xbps-create -A noarch -n a-0.2_1 -s "pkg a" pkg_a
+	atf_check_equal $? 0
+	rm -rf pkg_a
+	xbps-rindex -a *.xbps
+	atf_check_equal $? 0
+	xbps-install -r rootdir --repository=$PWD -yu
+	atf_check_equal $? 0
+	tgt=$(readlink rootdir/foo)
+	rval=1
+	if [ -f rootdir/blah -a "$tgt" = "blah" ]; then
+		rval=0
+	fi
+	atf_check_equal $rval 0
+}
+
+atf_init_test_cases() {
+	atf_add_test_case issue20
+}