could be enabled by running the test suite with correct GIT_TEST_
environment set.
-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
-prerequisite when adding more strings for translation. See "Testing
-marked strings" in po/README for details.
+GIT_TEST_FAIL_PREREQS=<boolean> 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=<boolean> turns all strings marked for
+translation into gibberish if true. Used for spotting those tests that
+need to be marked with a C_LOCALE_OUTPUT prerequisite when adding more
+strings for translation. See "Testing marked strings" in po/README for
+details.
GIT_TEST_SPLIT_INDEX=<boolean> forces split-index mode on the whole
test suite. Accept any boolean values that are accepted by git-config.