debian/changelog

+tails-installer (5.0.13+dfsg-2) unstable; urgency=medium
+
+  * Deprecate running Tails Installer outside of Tails (refs: Tails#16011)
+    Tails now comes as USB image, ISO images are only used for DVD
+    installation. Installing the flag file located at
+    /etc/tails-installer/deprecated-outside-of-Tails
+
+ -- Ulrike Uhlig <ulrike@debian.org>  Tue, 29 Jan 2019 14:10:50 +0100
+
 tails-installer (5.0.13+dfsg-1) unstable; urgency=medium
 
   * New upstream version: prepare for deprecation outside of Tails.

debian/rules

@@ -18,3 +18,5 @@ override_dh_auto_clean:
 override_dh_install:
 	python setup.py install --root=debian/tails-installer/ --install-layout=deb
 	dh_install
+	mkdir -p debian/tails-installer/etc/tails-installer
+	touch debian/tails-installer/etc/tails-installer/deprecated-outside-of-Tails