Merge branch '1.8'

CHANGES

@@ -232,6 +232,7 @@ Bugs fixed
 * #5960: LaTeX: modified PDF layout since September 2018 TeXLive update of
   :file:`parskip.sty`
 * #5958: versionadded directive causes crash with Python 3.5.0
+* #5995: autodoc: autodoc_mock_imports conflict with metaclass on Python 3.7
 
 Testing
 --------

sphinx/ext/autodoc/importer.py

@@ -58,7 +58,7 @@ class _MockObject:
 
     def __mro_entries__(self, bases):
         # type: (Tuple) -> Tuple
-        return bases
+        return (self.__class__,)
 
     def __getitem__(self, key):
         # type: (str) -> _MockObject

tests/test_ext_autodoc_importer.py

@@ -8,6 +8,7 @@
     :license: BSD, see LICENSE for details.
 """
 
+import abc
 import sys
 
 import pytest
@@ -60,3 +61,21 @@ def test_mock_does_not_follow_upper_modules():
     with mock(['sphinx.unknown.module']):
         with pytest.raises(ImportError):
             __import__('sphinx.unknown')
+
+
+@pytest.mark.skipif(sys.version_info < (3, 7), reason='Only for py37 or above')
+def test_abc_MockObject():
+    mock = _MockObject()
+
+    class Base:
+        @abc.abstractmethod
+        def __init__(self):
+            pass
+
+    class Derived(Base, mock.SubClass):
+        pass
+
+    obj = Derived()
+    assert isinstance(obj, Base)
+    assert isinstance(obj, _MockObject)
+    assert isinstance(obj.some_method(), Derived)