Use raise from instead of weird magic

jedi/inference/utils.py

@@ -1,6 +1,4 @@
 """ A universal module with functions / classes without dependencies. """
-import sys
-import contextlib
 import functools
 import re
 import os
@@ -34,7 +32,6 @@ class UncaughtAttributeError(Exception):
     """
     Important, because `__getattr__` and `hasattr` catch AttributeErrors
     implicitly. This is really evil (mainly because of `__getattr__`).
-    `hasattr` in Python 2 is even more evil, because it catches ALL exceptions.
     Therefore this class originally had to be derived from `BaseException`
     instead of `Exception`.  But because I removed relevant `hasattr` from
     the code base, we can now switch back to `Exception`.
@@ -63,17 +60,13 @@ def reraise_uncaught(func):
     difficult.  This decorator is to help us getting there by changing
     `AttributeError` to `UncaughtAttributeError` to avoid unexpected catch.
     This helps us noticing bugs earlier and facilitates debugging.
-
-    .. note:: Treating StopIteration here is easy.
-              Add that feature when needed.
     """
     @functools.wraps(func)
     def wrapper(*args, **kwds):
         try:
             return func(*args, **kwds)
-        except AttributeError:
+        except AttributeError as e:
-            exc_info = sys.exc_info()
+            raise UncaughtAttributeError(e) from e
-            UncaughtAttributeError(exc_info[1]).with_traceback(exc_info[2])
     return wrapper