Fix the tuple from rpartition being in wrong order when sub isn't

contained within the string

Author: skinnyBat

tests/snippets/strings.py

@@ -132,7 +132,9 @@
 assert '-'.join(['1', '2', '3']) == '1-2-3'
 assert 'HALLO'.isupper()
 assert "hello, my name is".partition("my ") == ('hello, ', 'my ', 'name is')
+assert "hello".partition("is") == ('hello', '', '')
 assert "hello, my name is".rpartition("is") == ('hello, my name ', 'is', '')
+assert "hello".rpartition("is") == ('', '', 'hello')
 assert not ''.isdecimal()
 assert '123'.isdecimal()
 assert not '\u00B2'.isdecimal()

vm/src/obj/objstr.rs

@@ -635,9 +635,9 @@ impl PyString {
             new_tup.swap(0, 1); // so it's in the right order
             new_tup.insert(1, vm.ctx.new_str(sub.clone()));
         } else {
-            new_tup.push(vm.ctx.new_str(value.clone()));
             new_tup.push(vm.ctx.new_str("".to_string()));
             new_tup.push(vm.ctx.new_str("".to_string()));
+            new_tup.push(vm.ctx.new_str(value.clone()));
         }
         vm.ctx.new_tuple(new_tup)
     }