commit 5affd23e6f42125998724787025080a24839266e
author Serhiy Storchaka <storchaka@gmail.com> Wed Apr 05 09:37:24 2017 +0300
committer GitHub <noreply@github.com> Wed Apr 05 09:37:24 2017 +0300
tree 8b7ca82362e78a32805b117d574082d512251d3c
parent 43ba8861e0ad044efafa46a7cc04e12ac5df640e

bpo-29762: More use "raise from None". (#569)

This hides unwanted implementation details from tracebacks.

Lib/_collections_abc.py

diff --git a/Lib/_collections_abc.py b/Lib/_collections_abc.py
index 005d884..e89e84b 100644
--- a/Lib/_collections_abc.py
+++ b/Lib/_collections_abc.py
@@ -589,7 +589,7 @@
         try:
             value = next(it)
         except StopIteration:
-            raise KeyError
+            raise KeyError from None
         self.discard(value)
         return value
 
@@ -808,7 +808,7 @@
         try:
             key = next(iter(self))
         except StopIteration:
-            raise KeyError
+            raise KeyError from None
         value = self[key]
         del self[key]
         return key, value