There is a warning in SourceTree when working with git. It confuse me for a long time:

This warning may caused by SourceTree which configured the templatedir to C:\Program Files\Git\share\git-core\templates and is not correct for 64 bit git on Windows. For 64 bit git it default install its templates to C:\Program Files\Git\share\git-core\templates.

To fix this warnings, either edit .gitconfig in the user directory (%USERPROFILE%/.gitconfig).

Or via command line:

Note: You may have git for Windows installed at other location, change the path set above.

UPDATE:

For mac user if your are using system git, the template path is /Library/Developer/CommandLineTools/usr/share/git-core/templates.