Check that version increases when adding packages to testing

When we try to compute_groups for a group which has a source or a binary with
a lower version than testing, throw an exception. In the cases where this can
happen, the exception is caught. In other cases, it is not and it serves as an
assert.

This can only happen when there are multiple candidates (from multiple suites)
changing the same source or binary.

This should fix the ordering issues tested in these tests:
- tpu-unstable-binnmu
- binnmu-tpu
- tpu-with-unstable-binnmu

With this change, it should be possible to accept binNMUs from *pu again.

Signed-off-by: Ivo De Decker <ivodd@debian.org>

britney.py

@@ -212,6 +212,7 @@ from britney2.utils import (log_and_format_old_libraries,
                             clone_nuninst, check_installability,
                             invalidate_excuses, compile_nuninst,
                             find_smooth_updateable_binaries, parse_provides,
+                            MigrationConstraintException,
                             )
 
 __author__ = 'Fabio Tranchitella and the Debian Release Team'
@@ -1598,6 +1599,13 @@ class Britney(object):
         # add the new binary packages (if we are not removing)
         if not is_removal:
             source_data = source_suite.sources[source_name]
+            source_ver_new = source_data.version
+            if source_name in sources_t:
+                source_data_old = sources_t[source_name]
+                source_ver_old = source_data_old.version
+                if apt_pkg.version_compare(source_ver_old,source_ver_new) > 0:
+                    raise MigrationConstraintException("trying src:%s %s, while %s has %s"%(source_name,source_ver_new,target_suite.name,source_ver_old))
+
             for pkg_id in source_data.binaries:
                 binary, ver, parch = pkg_id
                 if migration_architecture not in ['source', parch]:
@@ -1625,6 +1633,12 @@ class Britney(object):
                         skip.add(pkg_id)
                     continue
 
+                if binary in binaries_t[parch]:
+                    oldver = binaries_t[parch][binary].version
+                    if apt_pkg.version_compare(oldver,ver) > 0:
+                        raise MigrationConstraintException("trying %s %s from src:%s %s, while %s has %s"
+                            %(binary,ver,source_name,source_ver_new,target_suite.name,oldver))
+
                 adds.add(pkg_id)
 
         return (adds, rms, smoothbins, skip)
@@ -1907,9 +1921,15 @@ class Britney(object):
         solver = InstallabilitySolver(self.pkg_universe, self._inst_tester)
 
         for y in sorted((y for y in packages), key=attrgetter('uvname')):
+            try:
                 updates, rms, _, _ = self._compute_groups(y.package, y.suite, y.architecture, y.is_removal)
                 result = (y, frozenset(updates), frozenset(rms))
                 group_info[y] = result
+            except MigrationConstraintException as e:
+                rescheduled_packages.remove(y)
+                output_logger.info("not adding package to list: %s",(y.package))
+                output_logger.info("    got exception: %s"%(repr(e)))
+
 
         if nuninst:
             nuninst_orig = nuninst
@@ -1931,6 +1951,8 @@ class Britney(object):
                 comp_name = ' '.join(item.uvname for item in comp)
                 output_logger.info("trying: %s" % comp_name)
                 with start_transaction(suite_info, all_binaries, parent_transaction) as transaction:
+                    accepted = False
+                    try:
                         accepted, nuninst_after, failed_arch = self.try_migration(comp,
                                                                                   nuninst_last_accepted,
                                                                                   transaction)
@@ -1967,6 +1989,17 @@ class Britney(object):
                             output_logger.info("    got: %s", self.eval_nuninst(nuninst_after, compare_nuninst))
                             output_logger.info("    * %s: %s", failed_arch, ", ".join(broken))
 
+                    except MigrationConstraintException as e:
+                        transaction.rollback()
+                        output_logger.info("skipped: %s (%d, %d, %d)",
+                                           comp_name,
+                                           len(rescheduled_packages),
+                                           len(maybe_rescheduled_packages),
+                                           len(worklist)
+                                           )
+                        output_logger.info("    got exception: %s"%(repr(e)))
+
+                    if not accepted:
                         if len(comp) > 1:
                             output_logger.info("    - splitting the component into single items and retrying them")
                             worklist.extend([item] for item in comp)

britney2/utils.py

@@ -42,6 +42,9 @@ from britney2.consts import (VERSION, PROVIDES, DEPENDS, CONFLICTS,
 from britney2.migrationitem import MigrationItem, UnversionnedMigrationItem
 from britney2.policies import PolicyVerdict
 
+class MigrationConstraintException(Exception):
+    pass
+
 
 def ifilter_except(container, iterable=None):
     """Filter out elements in container