Upgrade to coverage 3.7.1 and have it auto-build itself on first use.

third_party/coverage-3.7.1/coverage/xmlreport.py

Index: third_party/coverage-3.7.1/coverage/xmlreport.py
diff --git a/third_party/coverage-3.6/coverage/xmlreport.py b/third_party/coverage-3.7.1/coverage/xmlreport.py
similarity index 96%
rename from third_party/coverage-3.6/coverage/xmlreport.py
rename to third_party/coverage-3.7.1/coverage/xmlreport.py
index 301bc8654653bd37107ec36c3e5f178a6798ca5c..26ac02ad13d06077a9e46da349c0b88ec13d919b 100644
--- a/third_party/coverage-3.6/coverage/xmlreport.py
+++ b/third_party/coverage-3.7.1/coverage/xmlreport.py
@@ -85,7 +85,12 @@ class XmlReporter(Reporter):
         outfile.write(self.xml_out.toprettyxml())
 
         # Return the total percentage.
-        return 100.0 * (lhits_tot + bhits_tot) / (lnum_tot + bnum_tot)
+        denom = lnum_tot + bnum_tot
+        if denom == 0:
+            pct = 0.0
+        else:
+            pct = 100.0 * (lhits_tot + bhits_tot) / denom
+        return pct
 
     def xml_file(self, cu, analysis):
         """Add to the XML report for a single file."""
@@ -112,7 +117,7 @@ class XmlReporter(Reporter):
         branch_stats = analysis.branch_stats()
 
         # For each statement, create an XML 'line' element.
-        for line in analysis.statements:
+        for line in sorted(analysis.statements):
             xline = self.xml_out.createElement("line")
             xline.setAttribute("number", str(line))