Re: [PATCH v3 1/3] t: document regression git safe.directory when using sudo

Johannes Schindelin [off-list ref] writes:

quoted

A new SUDO prerequisite is provided that does some sanity checking
to make sure the sudo command that will be used allows for passwordless
execution as root and doesn't mess with git execution paths, but
otherwise additional work will be required to ensure additional
commands behave as expected and that will be addressed in a later patch.

This part probably needs to be stressed, not just here but near the
part where we require IKNOWWHATIAMDOING=YES to be set.  For regular
interactive boxes, this test should pretty much be useless, as on a
normally configured machine with human users, it is likely that
"sudo" updates/restricts PATH to a limited set of directories and
exclude the path to our just-built-and-being-tested "git".

IOW, this is primarily (and likely to be solely) for a specialized
CI job in a very controlled environment.

quoted

+# this prerequisite should be added to all the tests, it not only prevents
+# the test from failing but also warms up any authentication cache sudo
+# might need to avoid asking for a password
+test_lazy_prereq SUDO '
+	sudo -n id -u >u &&
+	id -u root >r &&
+	test_cmp u r &&
+	command -v git >u &&
+	sudo command -v git >r &&

In my Ubuntu setup, `/bin/sh` is a symbolic link to `/bin/dash`, which
does not understand the `command`. It might make more sense to use `type`
here, but it is quite possible that `type git` uses a different output
format than `sudo type git` if they use different shells.

So with that in mind, shell portability is still an issue, but ...

Another complication is that the `/etc/sudoers` I have over here specifies

... /etc/sudoers (both people allowed to use and how environments
are futzed with) is not.  If your /etc/sudoers do not allow SUDO
prereq here to pass, then that is OK.