Also force LC_ALL in test scripts.

Noticed by Junichi Uekawa.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 1523d2e..3f8a6fe 100755
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -5,9 +5,10 @@
 
 # For repeatability, reset the environment to known value.
 LANG=C
+LC_ALL=C
 PAGER=cat
 TZ=UTC
-export LANG PAGER TZ
+export LANG LC_ALL PAGER TZ
 unset AUTHOR_DATE
 unset AUTHOR_EMAIL
 unset AUTHOR_NAME