It seems that gedit command line interface is a moving target. After the fix #174 from January 2016, now it's again broken! On Ubuntu 16.04 with gedit (v 3.18) and Debian testing (v 3.22), the gedit -w -s call yields:
gedit -w -s
Failed to register: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod:
Method "DescribeAll" with signature "" on interface "org.gtk.Actions" doesn't exist
I found a report for this issue (https://bugzilla.gnome.org/show_bug.cgi?id=742469) from Jan 2015. Apparently for gedit 3.14. It's not yet fixed, but a workaround is suggested, to replace the '-s' (standalone) option by 'new-window'. New git config looks like:
$ git config --global core.editor "gedit --wait --new-window"
I've tested one commit message (with one extra gedit window previously opened to check the new-window option) and it seems to work fine. I think 02-setup.md should be updated accordingly.
update gedit config