the use of 'tr' in the test suite isn't really portable

Some versions of 'tr' only accept octal codes if entered with three digits,
and therefor misinterpret the '\0' in the test suite.

Some versions of 'tr' reject the (needless) use of character classes.

Signed-off-by: H.Merijn Brand <h.m.brand@xs4all.nl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

test-sha1.sh

@@ -10,7 +10,7 @@ do
 		{
 			test -z "$pfx" || echo "$pfx"
 			dd if=/dev/zero bs=1048576 count=$cnt 2>/dev/null |
-			tr '[\0]' '[g]'
+			tr '\000' 'g'
 		} | ./test-sha1 $cnt
 	`
 	if test "$expect" = "$actual"
@@ -55,7 +55,7 @@ do
 		{
 			test -z "$pfx" || echo "$pfx"
 			dd if=/dev/zero bs=1048576 count=$cnt 2>/dev/null |
-			tr '[\0]' '[g]'
+			tr '\000' 'g'
 		} | sha1sum |
 		sed -e 's/ .*//'
 	`