add a couple of super hacky scripts for quickly testing subiquity changes

The first of these scripts mashes the current branch's code over that of
a pre-existing subiquity snap.

The second uses the first to mash the current branch's code over the
subiquity snap from an ISO and then creates a new ISO with this new
snap.

It's all a bit terrifying but being able to get your changes into a
bootable ISO in about 30s is quite a large improvement on building the
snap from scratch.

scripts/quick-test-this-branch.sh

@@ -0,0 +1,47 @@
+#!/bin/bash
+
+set -eux
+
+src="$(dirname "$(dirname "$(readlink -f "${0}")")")"
+old_iso="$(readlink -f "${1}")"
+new_iso="$(readlink -f "${2}")"
+
+tmpdir="$(mktemp -d)"
+cd "${tmpdir}"
+
+_MOUNTS=()
+
+do_mount_existing () {
+    local mountpoint="${!#}"
+    mount "$@"
+    _MOUNTS=("${mountpoint}" "${_MOUNTS[@]+"${_MOUNTS[@]}"}")
+}
+
+do_mount () {
+    local mountpoint="${!#}"
+    mkdir "${mountpoint}"
+    do_mount_existing "$@"
+}
+
+clean_mounts () {
+    for m in "${_MOUNTS[@]+"${_MOUNTS[@]}"}"; do
+        umount "${m}"
+    done
+    _MOUNTS=()
+}
+
+cleanup () {
+    clean_mounts
+    rm -rf "${tmpdir}"
+}
+
+trap cleanup EXIT
+
+do_mount $old_iso old_iso
+do_mount old_iso/casper/installer.squashfs installer
+
+$src/scripts/slimy-update-snap.sh installer/var/lib/snapd/seed/snaps/subiquity_*.snap subiquity_new.snap
+
+clean_mounts
+
+$src/scripts/inject-subiquity-snap.sh $old_iso subiquity_new.snap $new_iso

scripts/slimy-update-snap.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+
+# slimy-update-snap.sh $old_snap $new_snap
+
+set -eux
+
+src="$(dirname "$(dirname "$(readlink -f "${0}")")")"
+old="$(readlink -f "${1}")"
+new="$(readlink -f "${2}")"
+
+tmpdir="$(mktemp -d)"
+cd "${tmpdir}"
+
+_MOUNTS=()
+
+do_mount_existing () {
+    local mountpoint="${!#}"
+    mount "$@"
+    _MOUNTS=("${mountpoint}" "${_MOUNTS[@]+"${_MOUNTS[@]}"}")
+}
+
+do_mount () {
+    local mountpoint="${!#}"
+    mkdir "${mountpoint}"
+    do_mount_existing "$@"
+}
+
+add_overlay() {
+    local lower="$1"
+    local mountpoint="$2"
+    local work="$(mktemp -dp "${tmpdir}")"
+    if [ -n "${3-}" ]; then
+        local upper="${3}"
+    else
+        local upper="$(mktemp -dp "${tmpdir}")"
+    fi
+    chmod go+rx "${work}" "${upper}"
+    do_mount -t overlay overlay -o lowerdir="${lower}",upperdir="${upper}",workdir="${work}" "${mountpoint}"
+}
+
+
+cleanup () {
+    for m in "${_MOUNTS[@]+"${_MOUNTS[@]}"}"; do
+        umount "${m}"
+    done
+    rm -rf "${tmpdir}"
+}
+
+trap cleanup EXIT
+
+do_mount $old old
+
+add_overlay old new
+
+rm -rf new/lib/python3.6/site-packages/subiquity
+rm -rf new/lib/python3.6/site-packages/subiquitycore
+
+git -C $src archive HEAD subiquity subiquitycore | tar -C new/lib/python3.6/site-packages/ -x
+
+mksquashfs new $new -comp gzip -Xcompression-level 3