There are multiple places in org-attach.el where org-attach-commit isn't respected. This means that while adding a new attachment will respect the user setting and not make Git commits, various other commands will.
Emacs : GNU Emacs 25.2.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.22.10) of 2017-04-22 Package: Org mode version 9.0.8 (9.0.8-elpa @ /home/mir/.emacs.d/elpa/org-20170606/)
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