Catch specific exception rather than anything

The bare "except" also catches exceptions like "NameError" and
"SystemExit", which we really should not catch.  In scour.py, use the
most specific exception (NotFoundErr) and in the tests just catch any
"regular" exception.

Reported by flake8.

Signed-off-by: Niels Thykier <niels@thykier.net>

scour/scour.py

@@ -56,7 +56,7 @@ import re
 import sys
 import time
 import xml.dom.minidom
-from xml.dom import Node
+from xml.dom import Node, NotFoundErr
 from collections import namedtuple
 from decimal import Context, Decimal, InvalidOperation, getcontext
 
@@ -3619,7 +3619,7 @@ def scourXmlFile(filename, options=None):
     for node in all_nodes:
         try:
             node.setIdAttribute('id')
-        except:
+        except NotFoundErr:
             pass
 
     return doc