Just answered my own question with the help of the above comments… to switch to TextWrangler as the default for Git, you must open TextWrangler, click on TextWrangler in the tool bar and select “install command line tools” from the drop down. Then go into command line and type:
git config --global core.editor "edit -w"
Edit is the command that is understood in the command line which means to open a textWrangler file.