could be enabled by running the test suite with correct GIT_TEST_
environment set.
+GIT_TEST_FAIL_PREREQS<non-empty?> fails all prerequisites. This is
+useful for discovering issues with the tests where say a later test
+implicitly depends on an optional earlier test.
+
+There's a "FAIL_PREREQS" prerequisite that can be used to test for
+whether this mode is active, and e.g. skip some tests that are hard to
+refactor to deal with it. The "SYMLINKS" prerequisite is currently
+excluded as so much relies on it, but this might change in the future.
+
GIT_TEST_GETTEXT_POISON=<non-empty?> turns all strings marked for
translation into gibberish if non-empty (think "test -n"). Used for
spotting those tests that need to be marked with a C_LOCALE_OUTPUT