autopkgtest: Trigger lxc tests for linux updates

New kernels are prone to break LXC. In https://bugs.debian.org/779559 there is
a proposal for a flexible approach to add extra "reverse test dependencies".
Hardcode this trigger until this gets implemented.

autopkgtest.py

@@ -207,6 +207,11 @@ class AutoPackageTest(object):
                         tests.append((rdep_src, rdep_src_info[VERSION]))
                         reported_pkgs.add(rdep_src)
 
+        # Hardcode linux → lxc trigger until we get a more flexible
+        # implementation: https://bugs.debian.org/779559
+        if src == 'linux' and 'lxc' not in reported_pkgs:
+            tests.append(('lxc', self.britney.sources['testing']['lxc'][VERSION]))
+
         tests.sort(key=lambda s_v: s_v[0])
         return tests
 

tests/test_autopkgtest.py

@@ -1129,6 +1129,16 @@ lightgreen 1 i386 green 3
              'linux-meta-lts-grumpy': (False, {'fancy 1': {'amd64': 'RUNNING', 'i386': 'RUNNING'}})
             })
 
+    def test_kernel_triggers_lxc(self):
+        '''LXC test gets triggered by kernel uploads'''
+
+        self.data.add('lxc', False, {'Testsuite-Triggers': 'linux-libc-dev'},
+                      testsuite='autopkgtest')
+
+        self.do_test(
+            [('linux-libc-dev', {'Source': 'linux'}, None)],
+            {'linux': (False, {'lxc 1': {'amd64': 'RUNNING', 'i386': 'RUNNING'}})})
+
     def test_disable_adt(self):
         '''Run without autopkgtest requests'''