SF #950057: itertools.chain doesn't "process" exceptions as they occur

Both cycle() and chain() were handling exceptions only when switching
input sources.  The patch makes the handle more immediate.

diff --git a/Misc/NEWS b/Misc/NEWS
index 8c3f56cef98d83e8822ae4d1d8df5c23b743a968..c331a13b113181c941c1885368a396361d71c8b0 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -42,6 +42,10 @@ Core and builtins
 Library
 -------
 
+- Bug #950057: itertools.chain() and itertools.cycle() now handle
+               exceptions immediately instead of waiting until the
+               input source is updated.
+
 - Bug #931848: Fix _sre.CODESIZE on 64-bit machines in UCS-4 mode.
 
 - Bug #938076: Consider output encoding in XMLGenerator.