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Documentation here: http://docs.python.org/library/pipes.html makes no mention of quote()
But the link to Source code: Lib/pipes.py http://hg.python.org/cpython/file/2.7/Lib/pipes.py has:
267 def quote(file):
268 """Return a shell-escaped version of the file string."""
269 for c in file:
270 if c not in _safechars:
271 break
272 else:
273 if not file:
274 return "''"
275 return file
276 # use single quotes, and put single quotes into double quotes
277 # the string $'b is then quoted as '$'"'"'b'
278 return "'" + file.replace("'", "'\"'\"'") + "'"
First _ever_ bug report, apologies if this is incorrect.

Thanks for the report.
pipes.quote used to be an undocumented helper function in pipes. When we decided to make it public, we moved it to the shlex module. Therefore you'll find that as of Python 3.3 the source code has moved to shlex and it is documented in the shlex documentation.