mingw: fix t5601-clone.sh

Since baaf233 (connect: improve check for plink to reduce false
positives, 2015-04-26), t5601 writes out a `plink.exe` for testing that
is actually a shell script. So the assumption that the `.exe` extension
implies that the file is *not* a shell script is now wrong.

Since there was no love for the idea of allowing `.exe` files to be
shell scripts on Windows, let's go the other way round: *make*
`plink.exe` a real `.exe`.

This fixes t5601-clone.sh in Git for Windows' SDK.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t5601-clone.sh b/t/t5601-clone.sh
index 9b34f3c..e40fc26 100755
--- a/t/t5601-clone.sh
+++ b/t/t5601-clone.sh
@@ -4,6 +4,9 @@
 
 . ./test-lib.sh
 
+X=
+test_have_prereq !MINGW || X=.exe
+
 test_expect_success setup '
 
 	rm -fr .git &&
@@ -282,14 +285,9 @@
 
 setup_ssh_wrapper () {
 	test_expect_success 'setup ssh wrapper' '
-		write_script "$TRASH_DIRECTORY/ssh-wrapper" <<-\EOF &&
-		echo >>"$TRASH_DIRECTORY/ssh-output" "ssh: $*" &&
-		# throw away all but the last argument, which should be the
-		# command
-		while test $# -gt 1; do shift; done
-		eval "$1"
-		EOF
-		GIT_SSH="$TRASH_DIRECTORY/ssh-wrapper" &&
+		cp "$GIT_BUILD_DIR/test-fake-ssh$X" \
+			"$TRASH_DIRECTORY/ssh-wrapper$X" &&
+		GIT_SSH="$TRASH_DIRECTORY/ssh-wrapper$X" &&
 		export GIT_SSH &&
 		export TRASH_DIRECTORY &&
 		>"$TRASH_DIRECTORY"/ssh-output
@@ -297,8 +295,8 @@
 }
 
 copy_ssh_wrapper_as () {
-	cp "$TRASH_DIRECTORY/ssh-wrapper" "$1" &&
-	GIT_SSH="$1" &&
+	cp "$TRASH_DIRECTORY/ssh-wrapper$X" "${1%$X}$X" &&
+	GIT_SSH="${1%$X}$X" &&
 	export GIT_SSH
 }