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

This hides unwanted implementation details from tracebacks.

1 files changed, 1 insertions, 1 deletions

diff --git a/Lib/dis.py b/Lib/dis.py
index 0794b7f..f93d5b2 100644
--- a/Lib/dis.py
+++ b/Lib/dis.py
@@ -72,7 +72,7 @@ def distb(tb=None, *, file=None):
         try:
             tb = sys.last_traceback
         except AttributeError:
-            raise RuntimeError("no last traceback to disassemble")
+            raise RuntimeError("no last traceback to disassemble") from None
         while tb.tb_next: tb = tb.tb_next
     disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file)