tox-config: isort < 5 (to prevent flake8 failure); reorder imports …

…because `isort 4` and `isort 5` do not agree regarding import order

src/Products/MailHost/MailHost.py

@@ -41,16 +41,15 @@
 from OFS.role import RoleManager
 from OFS.SimpleItem import Item
 from Persistence import Persistent
+from Products.MailHost.decorator import synchronized
+from Products.MailHost.interfaces import IMailHost
 from zope.interface import implementer
 from zope.sendmail.delivery import DirectMailDelivery
 from zope.sendmail.delivery import QueuedMailDelivery
 from zope.sendmail.delivery import QueueProcessorThread
 from zope.sendmail.maildir import Maildir
 from zope.sendmail.mailer import SMTPMailer
 
-from Products.MailHost.decorator import synchronized
-from Products.MailHost.interfaces import IMailHost
-
 
 queue_threads = {}  # maps MailHost path -> queue processor threads
 

src/Products/MailHost/SendMailTag.py

@@ -14,7 +14,6 @@
 from DocumentTemplate._DocumentTemplate import render_blocks
 from DocumentTemplate.DT_String import String
 from DocumentTemplate.DT_Util import parse_params
-
 from Products.MailHost.MailHost import MailBase
 from Products.MailHost.MailHost import MailHostError
 

src/Products/MailHost/exportimport.py

@@ -15,11 +15,10 @@
 
 import six
 
-from zope.component import adapts
-
 from Products.GenericSetup.interfaces import ISetupEnviron
 from Products.GenericSetup.utils import XMLAdapterBase
 from Products.MailHost.interfaces import IMailHost
+from zope.component import adapts
 
 
 class MailHostXMLAdapter(XMLAdapterBase):

tox.ini

@@ -43,7 +43,7 @@ commands =
     - flake8 --format=html --doctests src setup.py
     flake8 --doctests src setup.py
 deps =
-    isort
+    isort < 5
     flake8
     # helper to generate HTML reports:
     flake8-html