Alternative removed on update removes current provider's symlink

[st3r4g]

After the update that removed the tar alternative group in void today, I noticed that xbps removed the symlink when bsdtar was updated, even though my current provider and owner of the symlink was gtar. Here is a test case to reproduce (please adjust test name and file placement):

diff --git a/tests/xbps/xbps-alternatives/main_test.sh b/tests/xbps/xbps-alternatives/main_test.sh
index 5dd1310d..9c235911 100644
--- a/tests/xbps/xbps-alternatives/main_test.sh
+++ b/tests/xbps/xbps-alternatives/main_test.sh
@@ -801,6 +801,45 @@ replace_alternative_with_symlink_body() {
        atf_check_equal $? 0
 }
 
+newtest_head() {
+       atf_set "descr" "Alternative removed on update removes current provider's symlink"
+}
+
+newtest_body() {
+       mkdir -p tar/usr/bin/ bsdtar/usr/bin
+       touch tar/usr/bin/gtar bsdtar/usr/bin/bsdtar
+       mkdir repo
+
+       cd repo
+       xbps-create -n tar-1.0_1 -s tar -A noarch --alternatives 'tar:tar:/usr/bin/gtar' ../tar
+       atf_check_equal $? 0
+       xbps-create -n bsdtar-1.0_1 -s bsdtar -A noarch --alternatives 'tar:tar:/usr/bin/bsdtar' ../bsdtar
+       atf_check_equal $? 0
+       xbps-rindex -a *xbps
+       atf_check_equal $? 0
+       cd ..
+
+       xbps-install -r root --repo=repo -y tar bsdtar
+       atf_check_equal $? 0
+       link=$(readlink -v root/usr/bin/tar)
+       atf_check_equal $? 0
+       atf_check_equal $link gtar
+
+       cd repo/
+       xbps-create -n bsdtar-1.0_2 -s bsdtar -A noarch ../bsdtar
+       atf_check_equal $? 0
+       xbps-rindex -a bsdtar-1.0_2.noarch.xbps
+       atf_check_equal $? 0
+       cd ..
+
+       xbps-install -r root --repo=repo -yu
+       atf_check_equal $? 0
+
+       link=$(readlink -v root/usr/bin/tar)
+       atf_check_equal $? 0
+       atf_check_equal $link gtar
+}
+
 atf_init_test_cases() {
        atf_add_test_case register_one
        atf_add_test_case register_one_dangling
@@ -821,4 +860,5 @@ atf_init_test_cases() {
        atf_add_test_case respect_current_provider
        atf_add_test_case prune_leftover_groups
        atf_add_test_case replace_alternative_with_symlink
+       atf_add_test_case newtest
 }