De-implement non-working / testing copy_internals from dml

The DML constructs will need to have traverse_internals
symbols set up; as there are currently non-working /non-used
_copy_internals methods, just remove these for now as they
are unlikely to be working correctly in any case.

Additionally remove an errant "return" statement noted
on the same issue from the MySQL dialect.

Fixes: #5060
Change-Id: I289005af04192e4c755d53244b1ea0711c266c6c

1 files changed, 3 insertions, 16 deletions

diff --git a/lib/sqlalchemy/sql/dml.py b/lib/sqlalchemy/sql/dml.py
index 66e92a63c..8b62e57e1 100644
--- a/lib/sqlalchemy/sql/dml.py
+++ b/lib/sqlalchemy/sql/dml.py
@@ -15,7 +15,6 @@ from .base import _from_objects
 from .base import _generative
 from .base import DialectKWArgs
 from .base import Executable
-from .elements import _clone
 from .elements import and_
 from .elements import ClauseElement
 from .elements import Null
@@ -204,6 +203,9 @@ class UpdateBase(
 
         self._hints = self._hints.union({(selectable, dialect_name): text})
 
+    def _copy_internals(self, **kw):
+        raise NotImplementedError()
+
 
 class ValuesBase(UpdateBase):
     """Supplies support for :meth:`.ValuesBase.values` to
@@ -623,12 +625,6 @@ class Insert(ValuesBase):
         self.include_insert_from_select_defaults = include_defaults
         self.select = coercions.expect(roles.DMLSelectRole, select)
 
-    def _copy_internals(self, clone=_clone, **kw):
-        # TODO: coverage
-        self.parameters = self.parameters.copy()
-        if self.select is not None:
-            self.select = _clone(self.select)
-
 
 class Update(ValuesBase):
     """Represent an Update construct.
@@ -785,11 +781,6 @@ class Update(ValuesBase):
         else:
             return ()
 
-    def _copy_internals(self, clone=_clone, **kw):
-        # TODO: coverage
-        self._whereclause = clone(self._whereclause, **kw)
-        self.parameters = self.parameters.copy()
-
     @_generative
     def where(self, whereclause):
         """return a new update() construct with the given expression added to
@@ -921,7 +912,3 @@ class Delete(UpdateBase):
                 seen.update(item._cloned_set)
 
         return froms
-
-    def _copy_internals(self, clone=_clone, **kw):
-        # TODO: coverage
-        self._whereclause = clone(self._whereclause, **kw)