add another helper script

.gitignore

@@ -65,3 +65,6 @@ venv
 
 # probert as its pulled externally
 probert
+
+# installer isos
+*.iso

README.md

@@ -69,3 +69,5 @@ do this:
    ```
    $ kvm -m 1024 -hda target.img -serial stdio
    ```
+
+The first three steps are bundled into the script ./scripts/test-this-branch.sh.

scripts/test-this-branch.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+set -eux
+
+cd $(dirname $(dirname $(readlink -f $0)))
+
+snapcraft snap --output subiquity_test.snap
+urlbase=http://cdimage.ubuntu.com/ubuntu-server/daily-live/current
+isoname=$(distro-info -d)-live-$(dpkg --print-architecture).iso
+zsync ${urlbase}/${isoname}.zsync
+sudo ./scripts/inject-subquity-snap.sh ${isoname} subquity_test.snap custom.iso
+