Fix duplicate pkg registration overwriting the existing pkg

Update the tests:
- Enable and rename the duplicate_pkgs test to duplicate_pkgs_allowed,
  to make it more clear which we are testing.  Also switch to using the
  new_pkg function to make the test cleaner.
- Add a disabled duplicate_pkgs_allowed test in prep for that being supported.
- Teach the register_message test to use new_manifest() and fix the duplicate
  registration it was doing.

libpkg/pkg_ports.c

@@ -1289,6 +1289,10 @@ pkg_add_port(struct pkgdb *db, struct pkg *pkg, const char *input_path,
 	UT_string *message;
 	struct pkg_message *msg;
 
+	if (pkg_is_installed(db, pkg->name) != EPKG_END) {
+		return(EPKG_INSTALLED);
+	}
+
 	location = reloc;
 	if (pkg_rootdir != NULL)
 		location = pkg_rootdir;

tests/frontend/config.sh

@@ -3,31 +3,19 @@
 . $(atf_get_srcdir)/test_environment.sh
 tests_init \
 	empty_conf \
+	duplicate_pkgs_notallowed \
 	inline_repo \
 	nameserver
-	#duplicate_pkgs
+#	duplicate_pkgs_allowed \
 
-# This test is half finished to show problems with `pkg register'
-duplicate_pkgs_body() {
+duplicate_pkgs_allowed_body() {
 	cat << EOF > pkg.conf
 duplicatedefault: 2
 EOF
 
 	for n in 1 2; do
-		cat << EOF > test${n}.ucl
-name: test
-origin: test
-version: ${n}
-allowduplicate: true
-maintainer: test
-categories: [test]
-comment: a test
-www: http://test
-prefix: /
-desc: <<EOD
-Yet another test
-EOD
-EOF
+		new_pkg test${n} test ${n}
+		echo 'allowduplicate: true' >> test${n}.ucl
 
 	atf_check \
 		-e empty \
@@ -44,6 +32,29 @@ done
 		pkg info
 }
 
+duplicate_pkgs_notallowed_body() {
+	for n in 1 2; do
+		new_pkg test${n} test ${n}
+	done
+
+	atf_check \
+		-e empty \
+		-o match:"Installing test-1..." \
+		-s exit:0 \
+		pkg register -M test1.ucl
+
+	atf_check \
+		-e empty \
+		-s exit:70 \
+		pkg register -M test1.ucl
+
+	atf_check \
+		-e empty \
+		-o match:"test-1                         a test" \
+		-s exit:0 \
+		pkg info
+}
+
 empty_conf_body() {
 	touch pkg.conf
 

tests/frontend/register.sh

@@ -58,29 +58,20 @@ EOF
 }
 
 register_message_body() {
-	cat << EOF > +MANIFEST
-name: "test2"
-origin: "osef"
-version: "1"
-arch: "freebsd:*"
-maintainer: "non"
-prefix: "${TMPDIR}"
-www: "unknown"
-comment: "need one"
-desc: "here as well"
-EOF
+	new_manifest test1 1 "${TMPDIR}"
 	cat << EOF > +DISPLAY
 message
 EOF
 
-OUTPUT='test2-1:
+OUTPUT='test1-1:
 Always:
 message
 
 '
 	atf_check -o match:"message" pkg register -m .
-	atf_check -o inline:"${OUTPUT}" pkg info -D test2
+	atf_check -o inline:"${OUTPUT}" pkg info -D test1
 
+	new_manifest test2 1 "${TMPDIR}"
 	cat << EOF > +DISPLAY
 [
 	{ message: "hey"},