Fix inconsistent resolution order with zope.interface v5.

CHANGES.rst

@@ -40,6 +40,8 @@
 
 - Fix tests with transaction 3.0.
 
+- Fix inconsistent resolution order with zope.interface v5.
+
 5.5.1 (2018-10-25)
 ==================
 

src/ZODB/FileStorage/FileStorage.py

@@ -127,12 +127,12 @@ class TempFormatter(FileStorageFormatter):
         self._file = afile
 
 @implementer(
-        IStorage,
         IStorageRestoreable,
         IStorageIteration,
         IStorageUndoable,
         IStorageCurrentRecordIteration,
         IExternalGC,
+        IStorage,
         )
 class FileStorage(
     FileStorageFormatter,

src/ZODB/blob.py

@@ -733,7 +733,6 @@ class BlobStorageMixin(object):
         return self.fshelper.temp_dir
 
 
-@zope.interface.implementer(ZODB.interfaces.IBlobStorage)
 class BlobStorage(BlobStorageMixin):
     """A wrapper/proxy storage to support blobs.
     """

tox.ini

@@ -13,6 +13,8 @@ commands =
     zope-testrunner --test-path=src []
 deps =
     .[test]
+setenv =
+    ZOPE_INTERFACE_STRICT_IRO = 1
 
 [testenv:coverage]
 basepython = python3.7