Issue #17177: stop using imp in test_importlib
Prevent a possible double close of parent pipe fds when the subprocess
exec runs into an error.  Prevent a regular multi-close of the /dev/null
fd when any of stdin, stdout and stderr was set to DEVNULL.
news entry for subprocess double close fix.
Prevent a possible double close of parent pipe fds when the subprocess
exec runs into an error.  Prevent a regular multi-close of the /dev/null
fd when any of stdin, stdout and stderr was set to DEVNULL.
Make test_builtin work when executed directly
Stop using the deprecated unittest.TestCase.assertRaisesRegexp()
Describe 'surrogateescape' in the documentation.

Also, improve some docstring descriptions of the 'errors' parameter.

Closes #14015.
Merge with 3.3
Issue #17177: The imp module is pending deprecation.

To make sure there is no issue with code that is both Python 2 and 3
compatible, there are no plans to remove the module any sooner than
Python 4 (unless the community moves to Python 3 solidly before then).
merge
Issues #18058, 18057: Make importlib._bootstrap.NamespaceLoader
conform the the InspectLoader ABC. Perk of this is that runpy/-m can
now work with namespace packages.
Check that warnings.showwarning() is not changed.
Issue #18115: Abstract out managing the cleanup of modules to use in
loaders where C code provides the loaded module.
importlib.abc.SourceLoader.get_source() was re-raising SyntaxError and
UnicodeDecodeError as ImportError. That was over-reaching the point of
raising ImportError in get_source() (which is to signal the source
code was not found when it should have). Conflating the two exceptions
with ImportError could lead to masking errors with the source which
should be known outside of whether there was an error simply getting
the source to begin with.