Added note about signal handling.

pep-0042.txt

@@ -80,6 +80,15 @@ Standard Library
 
       http://sourceforge.net/bugs/?func=detailbug&bug_id=112317&group_id=5470
 
+    - signal handling doesn't always work as expected.  E.g. if
+      sys.stdin.readline() is interrupted by a (returning) signal
+      handler, it returns "".  It would be better to make it raise an
+      exception (corresponding to EINTR) or to restart.  But these
+      changes would have to applied to all places that can do blocking
+      interruptable I/O.  So it's a big project.
+
+      http://sourceforge.net/bugs/?func=detailbug&bug_id=110599&group_id=5470
+
     - Ensure that all .py files in the std library use 4-space indents and
       no hard tabs.  This was actually a PEP200 precondition for the
       release of 2.0b1, but got misinterpreted as the weaker condition that