If you want to contribute to Theano, have a look at the instructions here: http://deeplearning.net/software/theano/dev_start_guide.html
Theano-PyMC is actively merging new changes. If you have a pull request on the original respository and would like to move it here use the following commands in your local theano repo
# Go to your Theano Repo
cd /path/to/your/repo
# If you'd like to add theano-PyMC as a remote
git remote add pymc [email protected]:pymc-devs/Theano-PyMC.git
# Verify the changes. You should see the pymc-devs/Theano-PyMC.git
git remote -v
# Checkout the branch of your request
git checkout branch_name
# Push to Theano-PyMC
git push pymc branch_name
If you'd like to completely run this command instead
# If you'd like to replace this repo as a remote
git remote set-url origin [email protected]:pymc-devs/Theano-PyMC.git