revision 1.24 of copy.py

SF patch 518765 (Derek Harland): Bug in copy.py when used through
rexec.

When using a restricted environment, imports of copy will fail with an
AttributeError when trying to access types.CodeType.

Bugfix candidate (all the way back to 1.5.3, but at least 2.1.3 and
2.2.1).