test_Path.py: Fix path ordering when both sources are same size

The paths are sorted in an unexpected way. Test both cases (though
only one case happens per Python version), and document what is
going on behind the test case.

In Python 3.11 both the object and the list have the same size. The
object grew by 8 bytes compared to Python 3.10.

For #41

guppy/heapy/test/test_Path.py

@@ -765,7 +765,11 @@ def str_address(x): return '<address>'
         b = list(it)
         self.aseq(str(a), str(b))
 
-        self.aseq(o.getvalue(), """\
+        # The sort order is based on the source set's byid partition (see
+        # Path.PathsIter.reset), which sorts based on the size, then render
+        # (see Part.IdentityPartition.__init__)
+        if sys.getsizeof(y) > sys.getsizeof(ob):
+            self.aseq(o.getvalue(), """\
  0: hpy().Root.i0_sysdict
  0: Src.i0_modules['sys'].__dict__
  0: hpy().Root.i0_sysdict
@@ -781,6 +785,23 @@ def str_address(x): return '<address>'
  0: <1 list: <address>*1>[0]
  1: <1 __main__.O: <address>>.x
 """.replace('__main__', self.__module__))
+        else:
+            self.aseq(o.getvalue(), """\
+ 0: hpy().Root.i0_sysdict
+ 0: Src.i0_modules['sys'].__dict__
+ 0: hpy().Root.i0_sysdict
+ 0: hpy().Root.i0_sysdict
+ 0: Src[0][0][0]
+ 0: Src[0][0][0]
+ 0: Src[0]
+ 0: Src.x
+ 0: <1 list: <address>*1>[0]
+ 0: <1 list: <address>*1>[0]
+ 0: <1 __main__.O: <address>>.x
+ 1: <1 list: <address>*1>[0]
+ 0: <1 __main__.O: <address>>.x
+ 1: <1 list: <address>*1>[0]
+""".replace('__main__', self.__module__))
 
     def test_2(self):
         # To assist interactivity,