When trying to write new bytecode, importlib was not catching the IOError
thrown if the file happened to be read-only to keep the failure silent.

Fixes issue #7187. Thanks, Dave Malcolm for the report and analysis of the
problem.
diff --git a/Misc/NEWS b/Misc/NEWS
index 0b98ccb..94c16bb 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -123,6 +123,9 @@
 Library
 -------
 
+- Issue #7187: Importlib would not silence the IOError raised when trying to
+  write new bytecode when it was made read-only.
+
 - Issue #7264: Fix a possible deadlock when deallocating thread-local objects
   which are part of a reference cycle.