I am using Windows 10, and I have found two ways to eliminate the passphrase prompting.
Make sure the ssh agent is started and you have added your key
$ eval "$(ssh-agent -s)"
$ ssh-add ~/.ssh/id_rsa
The second command will prompt you for your passphrase, and then you will not be prompted for any other git commands run in this session.
You will need to run these commands again for every new bash session
Remove the passphrase from you key file:
$ ssh-keygen -p -f ~/.ssh/id_rsa
When prompted, just strike enter key for the new passphrase.
Option 2 will permanently remove the passphrase for all git commands. Of course it also makes you key file "unsecured"
Note: If you are using git desktop GUI ( Version 1.04+) Option 2 is required for the GUI to work.