t4204: do not let $name variable clobbered

test_patch_id_file_order shell function uses $name variable to hold
one filename, and calls another shell function calc_patch_id as a
downstream of one pipeline.  The called function, however, also uses
the same $name variable.  With a shell implementation that runs the
callee in the current shell environment, the caller's $name would
be clobbered by the callee's use of the same variable.

This hasn't been an issue with dash and bash.  ksh93 reveals the
breakage in the test script.

Fix it by using a distinct variable name in the callee.

Reported-by: Armin Kunaschik <megabreit@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4204-patch-id.sh

@@ -30,11 +30,11 @@ test_expect_success 'patch-id output is well-formed' '
 
 #calculate patch id. Make sure output is not empty.
 calc_patch_id () {
-	name="$1"
+	patch_name="$1"
 	shift
 	git patch-id "$@" |
-	sed "s/ .*//" >patch-id_"$name" &&
-	test_line_count -gt 0 patch-id_"$name"
+	sed "s/ .*//" >patch-id_"$patch_name" &&
+	test_line_count -gt 0 patch-id_"$patch_name"
 }
 
 get_top_diff () {