Handle variant <remove> possibilities in anaconda3

packages/anaconda3.xml

@@ -15,10 +15,28 @@
   <upgrade include="install" />
 
   <remove cmd='cmd /c %WPKGSOFTWARE%\wpkg\tools\waitforprocess.cmd Un_A.exe' />
-  <remove cmd='c:\anaconda3\uninstall-anaconda3.exe /S' />
+
+  <!-- older versions of anaconda used uninstall-anaconda.exe ... -->
+  <remove cmd='c:\anaconda3\uninstall-anaconda.exe /S'>
+    <condition>
+      <check type="file" condition="exists" path="c:\anaconda3\uninstall-anaconda.exe" />
+    </condition>
+  </remove>
+
+  <!-- ... whereas current versions use uninstall-anaconda3.exe -->
+  <remove cmd='c:\anaconda3\uninstall-anaconda3.exe /S'>
+    <condition>
+      <check type="file" condition="exists" path="c:\anaconda3\uninstall-anaconda3.exe" />
+    </condition>
+  </remove>
+
   <remove cmd='cmd /c %WPKGSOFTWARE%\wpkg\tools\waitforprocess.cmd Un_A.exe' />
 
-  <remove cmd='reg delete HKLM\software\ucam_wpkg.cam.ac.uk /v anaconda3 /f'/>
+  <remove cmd='reg delete HKLM\software\ucam_wpkg.cam.ac.uk /v anaconda3 /f'>
+    <condition>
+      <check type='registry' condition='exists' path='HKLM\software\ucam_wpkg.cam.ac.uk\anaconda3' />
+    </condition>
+  </remove>
 
   </package>