t4015: simplify sed command that is not even seen by sed

Noticed by Andreas Schwab; \<LF> inside a double quotes pair is
eaten by the shell to become an empty string and is not doing
anything.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 0126154..604a838 100755 (executable)
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -146,7 +146,6 @@ test_expect_success 'ignore-blank-lines: only new lines' '
        test_seq 5 >x &&
        git update-index x &&
        test_seq 5 | sed "/3/i\\
-\
 " >x &&
        git diff --ignore-blank-lines >out &&
        >expect &&