build: Update git.mk from upstream
tests: Comment out an overly-stringent assert in standalone-individuals

As described in the comment added to the test, the core of folks needs a
bit of in-depth work to make the behaviour do what the test expects.
This work needs to be done at some point, but I don’t have time for it
now.

https://bugzilla.gnome.org/show_bug.cgi?id=723540