Fix deletion of last character in levenshtein distance

Without this change, "git tags" will not suggest "git tag"
(it will only suggest "git status"), and "git statusx" will
not suggest anything.

Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

levenshtein.c

@@ -25,7 +25,7 @@ int levenshtein(const char *string1, const char *string2,
 					row2[j + 1] > row0[j - 1] + w)
 				row2[j + 1] = row0[j - 1] + w;
 			/* deletion */
-			if (j + 1 < len2 && row2[j + 1] > row1[j + 1] + d)
+			if (row2[j + 1] > row1[j + 1] + d)
 				row2[j + 1] = row1[j + 1] + d;
 			/* insertion */
 			if (row2[j + 1] > row2[j] + a)