tests: enclose $PERL_PATH in double quotes

Otherwise it will be split at a space after "Program" when it is set
to "\\Program Files\perl" or something silly like that.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t6011-rev-list-with-bad-commit.sh b/t/t6011-rev-list-with-bad-commit.sh
index b2c6125..bbb0581 100755
--- a/t/t6011-rev-list-with-bad-commit.sh
+++ b/t/t6011-rev-list-with-bad-commit.sh
@@ -37,7 +37,7 @@
 
 test_expect_success 'corrupt second commit object' \
    '
-   $PERL_PATH -i.bak -pe "s/second commit/socond commit/" .git/objects/pack/*.pack &&
+   "$PERL_PATH" -i.bak -pe "s/second commit/socond commit/" .git/objects/pack/*.pack &&
    test_must_fail git fsck --full
    '