scour.py: minor rearrangement for the sake of clarity

There has been a minor rearrangement of the code that handles the children
of the element being serialized: The relevant `if' statement has had its
condition effectively negated and thus has also had its consequent and
alternative swapped; now, there is a very short consequent, followed by a
very long alternative, rather than a very long consequent followed by a
very short alternative.

scour/scour.py

@@ -3282,9 +3282,12 @@ def serializeXML(element, options, ind=0, preserveWhitespace=False):
             elif attrValue == 'default':
                 preserveWhitespace = False
 
-    # if no children, self-close
     children = element.childNodes
-    if children.length > 0:
+    if children.length == 0:
+        outParts.append('/>')
+        if indent > 0:
+            outParts.append(newline)
+    else:
         outParts.append('>')
 
         onNewLine = False
@@ -3319,10 +3322,6 @@ def serializeXML(element, options, ind=0, preserveWhitespace=False):
         outParts.extend(['</', element.nodeName, '>'])
         if indent > 0:
             outParts.append(newline)
-    else:
-        outParts.append('/>')
-        if indent > 0:
-            outParts.append(newline)
 
     return "".join(outParts)