deploy_server: fix TypeError in deploy_server

BUG=None
TEST=None

Change-Id: I41abd32777fb1119c9924077d9fd2cf6d5445fc5
Reviewed-on: https://chromium-review.googlesource.com/395286
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
diff --git a/site_utils/deploy_server.py b/site_utils/deploy_server.py
index 7b26bab..3fe1cdd 100755
--- a/site_utils/deploy_server.py
+++ b/site_utils/deploy_server.py
@@ -265,7 +265,8 @@
             print('  %s' % server)
         print()
         print('To retry:')
-        print('  %s <options> %s' % (args[0], ' '.join(failed + skipped)))
+        print('  %s <options> %s' %
+              (str(args[0]), str(' '.join(failed + skipped))))
 
 
 if __name__ == '__main__':