BuildDependsPolicy: Make linux* wait on corresponding -meta package

We want to treat linux-$flavor and linux-meta-$flavor as one set in
britney which goes in together or not at all. We never want to promote
linux-$flavor without the accompanying linux-meta-$flavor.

Introduce a synthetic linux* → linux-meta* build-dependency to enforce
this grouping.

britney2/policies/policy.py

@@ -959,7 +959,7 @@ class BuildDependsPolicy(BasePolicy):
 
         # analyze the dependency fields (if present)
         deps = source_data_srcdist.build_deps_arch
-        if deps:
+        if deps or item.package.startswith('linux'):
             v = self._check_build_deps(deps, DependencyType.BUILD_DEPENDS, build_deps_info, item,
                                        source_data_tdist, source_data_srcdist, excuse,
                                        get_dependency_solvers=get_dependency_solvers)
@@ -1056,6 +1056,34 @@ class BuildDependsPolicy(BasePolicy):
             binaries_t_a = binaries_t[arch]
             provides_t_a = provides_t[arch]
             arch_results[arch] = BuildDepResult.OK
+
+            # make linux* wait on corresponding -meta package
+            if source_name.startswith('linux'):
+                meta = source_name.replace('linux', 'linux-meta', 1)
+                try:
+                    meta_src = source_suite.sources[meta]
+                    meta_binaries = meta_src.binaries
+
+                    # Find a binary to build-depend on
+                    for binary in meta_binaries:
+                        dep_pkg_name = binary.package_name
+                        dep_pkg_version = binary.version
+                        break
+
+                    new_dep = '%s (>= %s)' % (dep_pkg_name, dep_pkg_version)
+
+                    if not deps:
+                        deps = new_dep
+                    elif new_dep not in deps:
+                        deps += ', %s' % new_dep
+
+                    self.logger.info('Synthesizing Build-Depends from %s to %s' % (source_name, new_dep))
+                except KeyError:
+                    pass
+
+            if not deps:
+                return verdict
+
             # for every dependency block (formed as conjunction of disjunction)
             for block_txt in deps.split(','):
                 block = parse_src_depends(block_txt, False, arch)

tests/test_autopkgtest.py

@@ -2072,6 +2072,59 @@ class AT(TestAutopkgtestBase):
         # everything from -meta
         self.assertEqual(exc['linux']['policy_info']['autopkgtest'], {'verdict': 'PASS'})
 
+    def test_kernel_waits_on_meta(self):
+        '''linux waits on linux-meta'''
+
+        self.data.add('dkms', False, {})
+        self.data.add('dkms', True, {})
+        self.data.add('fancy-dkms', False, {'Source': 'fancy', 'Depends': 'dkms (>= 1)'}, testsuite='autopkgtest-pkg-dkms')
+        self.data.add('fancy-dkms', True, {'Source': 'fancy', 'Depends': 'dkms (>= 1)'}, testsuite='autopkgtest-pkg-dkms')
+        self.data.add('linux-image-generic', False, {'Version': '0.1', 'Source': 'linux-meta', 'Depends': 'linux-image-1'})
+        self.data.add('linux-image-1', False, {'Source': 'linux'}, testsuite='autopkgtest')
+        self.data.add('linux-firmware', False, {'Source': 'linux-firmware'}, testsuite='autopkgtest')
+
+        self.swift.set_results({'autopkgtest-testing': {
+            'testing/i386/f/fancy/20150101_090000@': (0, 'fancy 0.5', tr('passedbefore/1')),
+            'testing/i386/l/linux/20150101_100000@': (0, 'linux 2', tr('linux-meta/0.2')),
+            'testing/amd64/l/linux/20150101_100000@': (0, 'linux 2', tr('linux-meta/0.2')),
+            'testing/i386/l/linux-firmware/20150101_100000@': (0, 'linux-firmware 2', tr('linux-firmware/2')),
+            'testing/amd64/l/linux-firmware/20150101_100000@': (0, 'linux-firmware 2', tr('linux-firmware/2')),
+        }})
+
+        self.run_it(
+            [('linux-image-generic', {'Version': '0.2', 'Source': 'linux-meta', 'Depends': 'linux-image-2'}, None),
+             ('linux-image-2', {'Version': '2', 'Source': 'linux'}, 'autopkgtest'),
+             ('linux-firmware', {'Version': '2', 'Source': 'linux-firmware'}, 'autopkgtest'),
+            ],
+            {'linux-meta': (False, {'fancy': {'amd64': 'RUNNING-ALWAYSFAIL', 'i386': 'RUNNING'},
+                                    'linux/2': {'amd64': 'PASS', 'i386': 'PASS'}
+                                   }),
+             # no tests, but should wait on linux-meta
+             'linux': (False, {}),
+             # this one does not have a -meta, so don't wait
+             'linux-firmware': (True, {'linux-firmware/2': {'amd64': 'PASS', 'i386': 'PASS'}}),
+            },
+            {'linux': [('excuses', 'Build-Depends(-Arch): linux <a href="#linux-meta">linux-meta</a> (not considered)'),
+                       ('dependencies', {'blocked-by': ['linux-meta']})]
+            }
+        )
+
+        # now linux-meta is ready to go
+        self.swift.set_results({'autopkgtest-testing': {
+            'testing/i386/f/fancy/20150101_100000@': (0, 'fancy 1', tr('linux-meta/0.2')),
+            'testing/amd64/f/fancy/20150101_100000@': (0, 'fancy 1', tr('linux-meta/0.2')),
+        }})
+        self.run_it(
+            [],
+            {'linux-meta': (True, {'fancy/1': {'amd64': 'PASS', 'i386': 'PASS'},
+                                   'linux/2': {'amd64': 'PASS', 'i386': 'PASS'}}),
+             'linux': (True, {}),
+             'linux-firmware': (True, {'linux-firmware/2': {'amd64': 'PASS', 'i386': 'PASS'}}),
+            },
+            {'linux': [('dependencies', {'migrate-after': ['linux-meta']})]
+            }
+        )
+
     ################################################################
     # Tests for special-cased packages
     ################################################################