migrations: Deprecate migration 0064 into a noop.

This ancient migration imports boto, which interferes
with our upgrade to boto3.

> git name-rev 8ae35211b5
8ae35211b5 tags/1.6.0~1924

We can safely assume nobody is upgrading from a server on <1.6.0,
since we have no supported platforms in common with those releases.

zerver/migrations/0064_sync_uploads_filesize_with_db.py

@@ -1,61 +1,8 @@
 # Generated by Django 1.10.5 on 2017-03-18 12:38
-import os
-from typing import Optional
-
-from boto.s3.connection import S3Connection
-from boto.s3.key import Key
-from django.conf import settings
 from django.db import migrations
-from django.db.backends.postgresql_psycopg2.schema import DatabaseSchemaEditor
-from django.db.migrations.state import StateApps
-
-
-class MissingUploadFileException(Exception):
-    pass
-
-def get_file_size_local(path_id: str) -> int:
-    file_path = os.path.join(settings.LOCAL_UPLOADS_DIR, 'files', path_id)
-    try:
-        size = os.path.getsize(file_path)
-    except OSError:
-        raise MissingUploadFileException
-    return size
-
-def sync_filesizes(apps: StateApps, schema_editor: DatabaseSchemaEditor) -> None:
-    attachments = apps.get_model('zerver', 'Attachment')
-    if settings.LOCAL_UPLOADS_DIR is not None:
-        for attachment in attachments.objects.all():
-            if attachment.size is None:
-                try:
-                    new_size = get_file_size_local(attachment.path_id)
-                except MissingUploadFileException:
-                    new_size = 0
-                attachment.size = new_size
-                attachment.save(update_fields=["size"])
-    else:
-        conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
-        bucket_name = settings.S3_AUTH_UPLOADS_BUCKET
-        bucket = conn.get_bucket(bucket_name, validate=False)
-        for attachment in attachments.objects.all():
-            if attachment.size is None:
-                file_key: Optional[Key] = bucket.get_key(attachment.path_id)
-                if file_key is None:
-                    new_size = 0
-                else:
-                    new_size = file_key.size
-                attachment.size = new_size
-                attachment.save(update_fields=["size"])
-
-def reverse_sync_filesizes(apps: StateApps, schema_editor: DatabaseSchemaEditor) -> None:
-    """Does nothing"""
-    return None
 
 class Migration(migrations.Migration):
 
     dependencies = [
         ('zerver', '0063_realm_description'),
     ]
-
-    operations = [
-        migrations.RunPython(sync_filesizes, reverse_sync_filesizes),
-    ]