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/multiprocessing/context.py

diff --git a/Lib/multiprocessing/context.py b/Lib/multiprocessing/context.py
index 623f6fb..a3d491b 100644
--- a/Lib/multiprocessing/context.py
+++ b/Lib/multiprocessing/context.py
@@ -189,7 +189,7 @@
         try:
             ctx = _concrete_contexts[method]
         except KeyError:
-            raise ValueError('cannot find context for %r' % method)
+            raise ValueError('cannot find context for %r' % method) from None
         ctx._check_available()
         return ctx