Avoid runtime dependency on plone.app.upgrade

news/142.bugfix

@@ -0,0 +1 @@
+Remove runtime dependency on plone.app.upgrade. @davisagli

src/plone/volto/bbb.py

@@ -1,4 +1,8 @@
 # flake8: noqa
+from types import ModuleType
+
+import sys
+
 
 try:
     from plone.base.interfaces import IPloneSiteRoot
@@ -9,3 +13,26 @@
     from plone.base.utils import get_installer
 except ImportError:
     from Products.CMFPlone.utils import get_installer
+
+
+# This was copied from plone.app.upgrade
+# to avoid a hard dependency on it.
+def alias_module(name, target):
+    parts = name.split(".")
+    i = 0
+    module = None
+    while i < len(parts) - 1:
+        i += 1
+        module_name = ".".join(parts[:i])
+        try:
+            __import__(module_name)
+        except ImportError:
+            new_module = ModuleType(module_name)
+            sys.modules[module_name] = new_module
+            if module is not None:
+                setattr(module, parts[i - 1], new_module)
+        module = sys.modules[module_name]
+
+    setattr(module, parts[-1], target)
+    # also make sure sys.modules is updated
+    sys.modules[module_name + "." + parts[-1]] = target

src/plone/volto/patches.py

@@ -1,9 +1,9 @@
-from plone.app.upgrade.utils import alias_module
 from plone.registry.interfaces import IRegistry
 from plone.rest.interfaces import IAPIRequest
 from plone.volto import content
 from plone.volto import interfaces
 from plone.volto import logger
+from plone.volto.bbb import alias_module
 from plone.volto.interfaces import IVoltoSettings
 from Products.SiteErrorLog.SiteErrorLog import _rate_restrict_burst
 from Products.SiteErrorLog.SiteErrorLog import _rate_restrict_period