Comment (by Roland Haas):

I requested changes. Basically, modern git actually defaults to $XDG_CONFIG_HOME/git/config for its config file and only falls back to ~/.gitconfig if the needed. Best is to query git about its options using git config --global user.email (taking care of failures etc if git is not in $PATH or otherwise not executable of course).

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2662/try-to-get-email-from-gitconfig