Shell syntax fix (leftover from a sync).

Signed-off-by: renmingshuai <renmingshuai@huawei.com>

regress/yes-head.sh

@@ -6,7 +6,7 @@ tid="yes pipe head"
 lines=`${SSH} -F $OBJ/ssh_proxy thishost 'sh -c "while true;do echo yes;done | _POSIX2_VERSION=199209 head -2000"' | (sleep 3 ; wc -l)`
 if [ $? -ne 0 ]; then
 	fail "yes|head test failed"
-+	lines=0
+	lines=0
 fi
 if [ $lines -ne 2000 ]; then
 	fail "yes|head returns $lines lines instead of 2000"