test-lib.sh: convert $TEST_DIRECTORY to an absolute path

If $TEST_DIRECTORY is specified in the environment, convert the value
to an absolute path to ensure that it remains valid even when 'cd' is
used.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Reviewed-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/test-lib.sh

@@ -26,6 +26,10 @@ then
 	# outside of t/, e.g. for running tests on the test library
 	# itself.
 	TEST_DIRECTORY=$(pwd)
+else
+	# ensure that TEST_DIRECTORY is an absolute path so that it
+	# is valid even if the current working directory is changed
+	TEST_DIRECTORY=$(cd "$TEST_DIRECTORY" && pwd) || exit 1
 fi
 if test -z "$TEST_OUTPUT_DIRECTORY"
 then