update sqlalchemy

lib/python3.5/site-packages/sqlalchemy/util/compat.py

@@ -1,5 +1,5 @@
 # util/compat.py
-# Copyright (C) 2005-2014 the SQLAlchemy authors and contributors
+# Copyright (C) 2005-2016 the SQLAlchemy authors and contributors
 # <see AUTHORS file>
 #
 # This module is part of SQLAlchemy and is released under
@@ -14,6 +14,7 @@ try:
 except ImportError:
     import dummy_threading as threading
 
+py36 = sys.version_info >= (3, 6)
 py33 = sys.version_info >= (3, 3)
 py32 = sys.version_info >= (3, 2)
 py3k = sys.version_info >= (3, 0)
@@ -176,27 +177,27 @@ from operator import attrgetter as dottedgetter
 if py3k:
     def reraise(tp, value, tb=None, cause=None):
         if cause is not None:
+            assert cause is not value, "Same cause emitted"
             value.__cause__ = cause
         if value.__traceback__ is not tb:
             raise value.with_traceback(tb)
         raise value
 
-    def raise_from_cause(exception, exc_info=None):
-        if exc_info is None:
-            exc_info = sys.exc_info()
-        exc_type, exc_value, exc_tb = exc_info
-        reraise(type(exception), exception, tb=exc_tb, cause=exc_value)
 else:
+    # not as nice as that of Py3K, but at least preserves
+    # the code line where the issue occurred
     exec("def reraise(tp, value, tb=None, cause=None):\n"
+         "    if cause is not None:\n"
+         "        assert cause is not value, 'Same cause emitted'\n"
          "    raise tp, value, tb\n")
 
-    def raise_from_cause(exception, exc_info=None):
-        # not as nice as that of Py3K, but at least preserves
-        # the code line where the issue occurred
-        if exc_info is None:
-            exc_info = sys.exc_info()
-        exc_type, exc_value, exc_tb = exc_info
-        reraise(type(exception), exception, tb=exc_tb)
+
+def raise_from_cause(exception, exc_info=None):
+    if exc_info is None:
+        exc_info = sys.exc_info()
+    exc_type, exc_value, exc_tb = exc_info
+    cause = exc_value if exc_value is not exception else None
+    reraise(type(exception), exception, tb=exc_tb, cause=cause)
 
 if py3k:
     exec_ = getattr(builtins, 'exec')
@@ -226,3 +227,37 @@ def with_metaclass(meta, *bases):
                 return type.__new__(cls, name, (), d)
             return meta(name, bases, d)
     return metaclass('temporary_class', None, {})
+
+
+from contextlib import contextmanager
+
+try:
+    from contextlib import nested
+except ImportError:
+    # removed in py3k, credit to mitsuhiko for
+    # workaround
+
+    @contextmanager
+    def nested(*managers):
+        exits = []
+        vars = []
+        exc = (None, None, None)
+        try:
+            for mgr in managers:
+                exit = mgr.__exit__
+                enter = mgr.__enter__
+                vars.append(enter())
+                exits.append(exit)
+            yield vars
+        except:
+            exc = sys.exc_info()
+        finally:
+            while exits:
+                exit = exits.pop()
+                try:
+                    if exit(*exc):
+                        exc = (None, None, None)
+                except:
+                    exc = sys.exc_info()
+            if exc != (None, None, None):
+                reraise(exc[0], exc[1], exc[2])