fix transition tests

tests/main/classic-ubuntu-core-transition-auth/task.yaml

@@ -12,7 +12,10 @@ execute: |
     dpkg --purge --force-depends snapd
     apt-get install -f -y
     install_build_snapd
-    snap install --${CORE_CHANNEL} ubuntu-core
+
+    snap download --${CORE_CHANNEL} ubuntu-core
+    snap ack ./ubuntu-core_*.assert
+    snap install ./ubuntu-core_*.snap
 
     mkdir -p /root/.snap/
     echo '{}' > /root/.snap/auth.json

tests/main/classic-ubuntu-core-transition-two-cores/task.yaml

@@ -22,7 +22,9 @@ execute: |
     systemctl stop snapd.service snapd.socket
     systemctl start snapd.service snapd.socket
 
-    snap install --${CORE_CHANNEL} ubuntu-core
+    snap download --${CORE_CHANNEL} ubuntu-core
+    snap ack ./ubuntu-core_*.assert
+    snap install ./ubuntu-core_*.snap
 
     cp /var/lib/snapd/state.json /var/lib/snapd/state.json.old
     cat /var/lib/snapd/state.json.old |jq -r '.data.snaps["core"].type="os"' > /var/lib/snapd/state.json

tests/main/classic-ubuntu-core-transition/task.yaml

@@ -42,7 +42,10 @@ execute: |
     mv state.json.new /var/lib/snapd/state.json
     systemctl start snapd.{service,socket}
 
-    snap install --${CORE_CHANNEL} ubuntu-core
+    snap download --${CORE_CHANNEL} ubuntu-core
+    snap ack ./ubuntu-core_*.assert
+    snap install ./ubuntu-core_*.snap
+
     snap install test-snapd-python-webserver
     snap interfaces | MATCH ":network +test-snapd-python-webserver"
     snap interfaces | MATCH ":network-bind +.*test-snapd-python-webserver"