Remove duplicated tests.
Merge removal of duplicated tests from 3.3.
Remove trailing whitespace.
Merge removal of trailing whitespace from 3.3.
Fix reference leak in _pickle.
Merge 3.3
#17065: Use process-unique key for winreg test.

Patch by Jeremy Kloth.
Merge #17065: Use process-unique key for winreg test.

Patch by Jeremy Kloth.
Issue #17670: Provide an example of expandtabs() usage.
Issue #17670: merge from 3.3
#15575: Clarify tutorial description of when modules are executed.
#15575: Clarify tutorial description of when modules are executed.