The attached patch would probably works better
Cheers,
Laurent Bigonville
diff -Nru lvm2-2.02.127/debian/lvm2.postinst lvm2-2.02.127/debian/lvm2.postinst
--- lvm2-2.02.127/debian/lvm2.postinst 2015-08-15 11:38:27.000000000 +0200
+++ lvm2-2.02.127/debian/lvm2.postinst 2015-08-31 13:36:07.000000000 +0200
@@ -11,6 +11,10 @@
if [ -x /usr/sbin/update-initramfs ]; then
update-initramfs -u
fi
+ if dpkg --compare-versions "$2" lt-nl "2.02.127-2~"; then
+ deb-systemd-helper purge lvm2-activation-early.service lvm2-activation.service >/dev/null
+ deb-systemd-helper unmask lvm2-activation-early.service lvm2-activation.service >/dev/null
+ fi
;;
esac
