tests: fix spread test failures on 18.04

This is important so that we get clean autopkgtest results for the
2.31 release in ubuntu 18.04 (and below).

interfaces/apparmor/backend_test.go

@@ -365,6 +365,9 @@ profile "snap.samba.smbd" (attach_disconnected) {
   # This is related to LP: #1666897
   @{INSTALL_DIR}/core/*/{,usr/}lib/@{multiarch}/{,**/}lib*.so* m,
 
+  # Read only access to the core snap-exec (needed on bionic)
+  @{INSTALL_DIR}/core/*/usr/lib/snapd/snap-exec m,
+
 snippet
 }
 `,

interfaces/apparmor/template.go

@@ -489,6 +489,9 @@ var classicJailmodeSnippet = `
   # Read only access to the core snap to load libc from.
   # This is related to LP: #1666897
   @{INSTALL_DIR}/core/*/{,usr/}lib/@{multiarch}/{,**/}lib*.so* m,
+
+  # Read only access to the core snap-exec (needed on bionic)
+  @{INSTALL_DIR}/core/*/usr/lib/snapd/snap-exec m,
 `
 
 // nfsSnippet contains extra permissions necessary for snaps and snap-confine

interfaces/builtin/time_control.go

@@ -68,6 +68,13 @@ dbus (receive)
     member=PropertiesChanged
     peer=(label=unconfined),
 
+# Required in bionic (Ubuntu 18.04)
+dbus (send)
+    bus=system
+    path=/org/freedesktop/timedate1
+    interface=org.freedesktop.DBus.Properties
+    member=GetAll,
+
 # As the core snap ships the timedatectl utility we can also allow
 # clients to use it now that they have access to the relevant
 # D-Bus methods for setting the time via timedatectl's set-time and

mdlint.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 #
 # see http://daringfireball.net/projects/markdown/syntax
 # for the "canonical" reference

tests/main/interfaces-timeserver-control/task.yaml

@@ -1,5 +1,10 @@
 summary: Check that timeserver interface works
 
+# This makes only sense on ubuntu-core because this snap will run inside
+# the core environment on a classic system we cannot really use this
+# on classic
+systems: [ubuntu-core-*]
+
 details: |
     This test makes sure that a snap using the timeserver-control interface
     can access timeserver information and update it.
@@ -12,7 +17,7 @@ prepare: |
 
 restore: |
     # Restore the initial timeserver
-    if [ -f timeserver.txt ]; then
+    if [ -s timeserver.txt ]; then
         timedatectl set-ntp "$(cat timeserver.txt)"
         rm -f timeserver.txt
     fi

tests/main/interfaces-timezone-control/task.yaml

@@ -1,5 +1,10 @@
 summary: Check that timezone interface works
 
+# This makes only sense on ubuntu-core because this snap will run inside
+# the core environment on a classic system we cannot really use this
+# on classic
+systems: [ubuntu-core-*]
+
 details: |
     This test makes sure that a snap using the timezone-control interface
     can access timezone information and update it.