Fix inconsistent Python union creator function naming (#8981)

tests/union_name_test/Foo.py

@@ -0,0 +1,90 @@
+# automatically generated by the FlatBuffers compiler, do not modify
+
+# namespace: union_name_test
+
+import flatbuffers
+from flatbuffers.compat import import_numpy
+np = import_numpy()
+
+class Foo(object):
+    __slots__ = ['_tab']
+
+    @classmethod
+    def GetRootAs(cls, buf, offset=0):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, offset)
+        x = Foo()
+        x.Init(buf, n + offset)
+        return x
+
+    @classmethod
+    def GetRootAsFoo(cls, buf, offset=0):
+        """This method is deprecated. Please switch to GetRootAs."""
+        return cls.GetRootAs(buf, offset)
+    # Foo
+    def Init(self, buf, pos):
+        self._tab = flatbuffers.table.Table(buf, pos)
+
+    # Foo
+    def Val(self):
+        o = flatbuffers.number_types.UOffsetTFlags.py_type(self._tab.Offset(4))
+        if o != 0:
+            return self._tab.Get(flatbuffers.number_types.Int32Flags, o + self._tab.Pos)
+        return 0
+
+def FooStart(builder):
+    builder.StartObject(1)
+
+def Start(builder):
+    FooStart(builder)
+
+def FooAddVal(builder, val):
+    builder.PrependInt32Slot(0, val, 0)
+
+def AddVal(builder, val):
+    FooAddVal(builder, val)
+
+def FooEnd(builder):
+    return builder.EndObject()
+
+def End(builder):
+    return FooEnd(builder)
+
+
+class FooT(object):
+
+    # FooT
+    def __init__(
+        self,
+        val = 0,
+    ):
+        self.val = val  # type: int
+
+    @classmethod
+    def InitFromBuf(cls, buf, pos):
+        foo = Foo()
+        foo.Init(buf, pos)
+        return cls.InitFromObj(foo)
+
+    @classmethod
+    def InitFromPackedBuf(cls, buf, pos=0):
+        n = flatbuffers.encode.Get(flatbuffers.packer.uoffset, buf, pos)
+        return cls.InitFromBuf(buf, pos+n)
+
+    @classmethod
+    def InitFromObj(cls, foo):
+        x = FooT()
+        x._UnPack(foo)
+        return x
+
+    # FooT
+    def _UnPack(self, foo):
+        if foo is None:
+            return
+        self.val = foo.Val()
+
+    # FooT
+    def Pack(self, builder):
+        FooStart(builder)
+        FooAddVal(builder, self.val)
+        foo = FooEnd(builder)
+        return foo