Avoid subprocess.Popen auto escaping my backslashes in grep
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I'm trying to write an svn pre-commit hook in python. Part of this involves checking the diff file to see if there are any actual file changes (as opposed to just property changes).

I have a working grep command which I can execute fine on the shell

    grep "^\(Added: \|Modified: \|Deleted: \)" diff filename | grep -v 'svn:'

However when I put it through subprocess.POpen it escapes all my backslashes, which knackers the regexp.

    Executing command: ['grep', '"^\\Added: \\|Modified: \\|Deleted: \\)", ...]

How do I avoid this?

NB: I'm aware that I can pipe results between subprocesses and I can do the two greps that way.  I need help getting the first one working first though :/

NB2: I also tried using filterdiff --clean instead and couldn't get it to work. Searching for Added, Modified or Deleted lines, removing those with 'svn:' in and checking I had some results seemed to work though.
