testing for cloned repository

I am using:
if [ -f ".git/remotes/origin" ]; then
	# this repository is a clone
fi
in a bash script to test if a repository was cloned and then do  
appropriate pulls and pushes which fit my situation.
Is this the proper way to test this or should I be using something  
different?

Thanks in advance for your help and for providing git.  I have been  
using it on my Linux and MacOSX machines without any problems.

Bob White