Extract a function to quote command-line arguments.
Extract a function to quote command-line arguments.

This is just a refactoring, with no change of functionality.  More to
come...

* subversion/tests/cmdline/svntest/main.py (_quote_arg): New function,
  using code taken from spawn_process().

  (spawn_process): Use the new function for quoting command-line
  arguments.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@865602 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion