Encourage rebase on forks by configuring the clone default for that

eclipse-jdt/eclipse.jdt#79

ua/org.eclipse.ua.releng/platformUa.setup

@@ -9,7 +9,7 @@
     xmlns:setup.targlets="http://www.eclipse.org/oomph/setup/targlets/1.0"
     xmlns:setup.workingsets="http://www.eclipse.org/oomph/setup/workingsets/1.0"
     xmlns:workingsets="http://www.eclipse.org/oomph/workingsets/1.0"
-    xsi:schemaLocation="http://www.eclipse.org/oomph/setup/git/1.0 http://git.eclipse.org/c/oomph/org.eclipse.oomph.git/plain/setups/models/Git.ecore http://www.eclipse.org/oomph/predicates/1.0 http://git.eclipse.org/c/oomph/org.eclipse.oomph.git/plain/setups/models/Predicates.ecore http://www.eclipse.org/oomph/setup/targlets/1.0 http://git.eclipse.org/c/oomph/org.eclipse.oomph.git/plain/setups/models/SetupTarglets.ecore http://www.eclipse.org/oomph/setup/workingsets/1.0 http://git.eclipse.org/c/oomph/org.eclipse.oomph.git/plain/setups/models/SetupWorkingSets.ecore http://www.eclipse.org/oomph/workingsets/1.0 http://git.eclipse.org/c/oomph/org.eclipse.oomph.git/plain/setups/models/WorkingSets.ecore"
+    xsi:schemaLocation="http://www.eclipse.org/oomph/setup/git/1.0 https://raw.githubusercontent.com/eclipse-oomph/oomph/master/setups/models/Git.ecore http://www.eclipse.org/oomph/predicates/1.0 https://raw.githubusercontent.com/eclipse-oomph/oomph/master/setups/models/Predicates.ecore http://www.eclipse.org/oomph/setup/targlets/1.0 https://raw.githubusercontent.com/eclipse-oomph/oomph/master/setups/models/SetupTarglets.ecore http://www.eclipse.org/oomph/setup/workingsets/1.0 https://raw.githubusercontent.com/eclipse-oomph/oomph/master/setups/models/SetupWorkingSets.ecore http://www.eclipse.org/oomph/workingsets/1.0 https://raw.githubusercontent.com/eclipse-oomph/oomph/master/setups/models/WorkingSets.ecore"
     name="ua"
     label="UA">
   <setupTask
@@ -37,6 +37,12 @@
         <value>remoteURI</value>
       </detail>
     </annotation>
+    <configSections
+        name="branch">
+      <properties
+          key="autoSetupRebase"
+          value="always"/>
+    </configSections>
     <description>Platform UA</description>
   </setupTask>
   <setupTask