Python Django迁移构建图有bug吗？

挤压迁移后运行测试时，我会收到以下错误报告：

lib/python2.7/site-packages/django/db/migrations/loader.py:220: KeyError

以下是源代码：

def build_graph(self):
    """
        Builds a migration dependency graph using both the disk and database.
        You'll need to rebuild the graph if you apply migrations. This isn't
        usually a problem as generally migration stuff runs in a one-shot process.
        """
    # Load disk data
    self.load_disk()
    # Load database data
    if self.connection is None:
        self.applied_migrations = set()
    else:
        recorder = MigrationRecorder(self.connection)
        self.applied_migrations = recorder.applied_migrations()
    # Do a first pass to separate out replacing and non-replacing migrations
    normal = {}
    replacing = {}
    for key, migration in self.disk_migrations.items():
        if migration.replaces:
            replacing[key] = migration
        else:
            normal[key] = migration
    # Calculate reverse dependencies - i.e., for each migration, what depends on it?
    # This is just for dependency re-pointing when applying replacements,
    # so we ignore run_before here.
    reverse_dependencies = {}
    for key, migration in normal.items():
        for parent in migration.dependencies:
            reverse_dependencies.setdefault(parent, set()).add(key)
    # Carry out replacements if we can - that is, if all replaced migrations
    # are either unapplied or missing.
    for key, migration in replacing.items():
        # Ensure this replacement migration is not in applied_migrations
        self.applied_migrations.discard(key)
        # Do the check. We can replace if all our replace targets are
        # applied, or if all of them are unapplied.
        applied_statuses = [(target in self.applied_migrations) for target in migration.replaces]
        can_replace = all(applied_statuses) or (not any(applied_statuses))
        if not can_replace:
            continue
        # Alright, time to replace. Step through the replaced migrations
        # and remove, repointing dependencies if needs be.
        for replaced in migration.replaces:
            if replaced in normal:
                # We don't care if the replaced migration doesn't exist;
                # the usage pattern here is to delete things after a while.
                del normal[replaced]
            for child_key in reverse_dependencies.get(replaced, set()):
                if child_key in migration.replaces:
                    continue
                normal[child_key].dependencies.remove(replaced)

最后一行抛出以下内容：

KeyError: ('my_app', u'0001_initial')

您可以看到问题是

正常
字典中不存在
子项。上一行检查子密钥是否在迁移中。替换，因为在这种情况下，子密钥迁移可能已被删除。但是，子密钥可能正在替换另一个迁移，因此即使它不在migration.replaces中，也可能已被删除

您同意这是django代码中的一个bug吗？
这似乎是django 1.7中的一个bug。从bug报告来看，它似乎是Django 1.8的一部分。我们将等到升级Django之后再压缩更多迁移。
我也遇到了同样的问题。我正在挤压几个应用程序，突然发现这个错误。我将尝试调试它，假设问题出现在最后一个压缩的应用程序中。