builders: fix mavenName sorting with py35

On Fedora 24, the mavenName vs group XML is sorted differently depending
on whether we're using Python 3.5 or Python 2.7. This was causing the
test to fail on Python 3.5.

Avoid relying on the dict sort behavior. Since there are only two XML
elements, write each one explicitly.

Change-Id: I53f88e53d7fc4d81e325b341b9444c4950044565

jenkins_jobs/modules/builders.py

@@ -1439,16 +1439,12 @@ def maven_builder(parser, xml_parent, data):
     """
     maven = XML.SubElement(xml_parent, 'org.jfrog.hudson.maven3.Maven3Builder')
 
-    required = {
-        'mavenName': 'name',
-        'goals': 'goals',
-    }
-
-    for key in required:
-        try:
-            XML.SubElement(maven, key).text = data[required[key]]
-        except KeyError:
-            raise MissingAttributeError(required[key])
+    try:
+        XML.SubElement(maven, 'mavenName').text = data['name']
+        XML.SubElement(maven, 'goals').text = data['goals']
+    except KeyError as e:
+        # exception will contain the missing key name
+        raise MissingAttributeError(e.arg[0])
 
     XML.SubElement(maven, 'rootPom').text = data.get('pom', 'pom.xml')
     XML.SubElement(maven, 'mavenOpts').text = data.get('maven-opts', '')