don't try to upload tarxz

tools/release

@@ -56,7 +56,7 b" if 'upload' in sys.argv:"
     # Make target dir if it doesn't exist
     print('1. Uploading IPython to archive.ipython.org')
     sh('ssh %s "mkdir -p %s/release/%s" ' % (archive_user, archive_dir, version))
-    sh('scp *.tar.gz *.tar.xz *.whl %s' % release_site)
+    sh('scp *.tar.gz *.whl %s' % release_site)
 
     print('2. Uploading backup files...')
     cd(ipbackupdir)