I understand this is an xcode warning/error, however, it happens when I try to run gitk --all from the command line.
gitk --all
YuFei-Zhus-MacBook-Pro:test phi
alias gk='gitk --all 2> /dev/null &' (I am on mac)
I have it in the ~/.bash_login file, and it solves it :D
you can also put it the .bashrc file