t/lib-chunk: work around broken "mv" on some vintage of macOS

When the destination is read-only, "mv" on some version of macOS
asks whether to replace the destination even though in the test its
stdin is not a terminal (and thus doesn't conform to POSIX[1]).

The helper to corrupt a chunk-file is designed to work on the
files like commit-graph and multi-pack-index files that are
generally read-only, so use "mv -f" to work around this issue.

Helped-by: SZEDER Gábor <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: gitster

t/lib-chunk.sh

@@ -13,5 +13,6 @@ corrupt_chunk_file () {
 	fn=$1; shift
 	perl "$TEST_DIRECTORY"/lib-chunk/corrupt-chunk-file.pl \
 		"$@" <"$fn" >"$fn.tmp" &&
-	mv "$fn.tmp" "$fn"
+	# some vintages of macOS 'mv' fails to overwrite a read-only file.
+	mv -f "$fn.tmp" "$fn"
 }