pin kail version to v0.16.1 since to avoid test failures with "latest"

* the currently latest kail release v0.17.0 did only publish source code
  artifacts, meaning we can not download the kail binary as tarball
* to avoid future test failures, this commit pins the kail version
  version to v0.16.1, which has been verified to work in the pipelines
* the value for KAIL_VERSION should be updated in the future whenever we
  deem this necessary and have verified that the needed binary artifacts
  have been published

Change-Id: I415e516a52694f292b0df3bd717edcbe1f3eff29
Signed-off-by: Jan Klare <jan.klare@bisdn.de>
diff --git a/makefiles/commands/kail.mk b/makefiles/commands/kail.mk
index f757a33..1a5047f 100644
--- a/makefiles/commands/kail.mk
+++ b/makefiles/commands/kail.mk
@@ -33,10 +33,13 @@
 #       + requires sudo and potential exists for overwrite conflict.
 # -----------------------------------------------------------------------
 KAIL_PATH ?= $(if $(WORKSPACE),$(WORKSPACE)/bin,/usr/local/bin)
+# pin kail version to current latest usable releases (v0.17.0 did only publish
+# source code, so we can't download the binary as tarball)
+KAIL_VERSION ?= "v0.16.1"
 kail-cmd  ?= $(KAIL_PATH)/kail
 $(kail-cmd):
 	mkdir -p "$(dir $@)"
-	etc/godownloader.sh -b .
+	etc/godownloader.sh -b . "${KAIL_VERSION}"
 	rsync -v --checksum kail "$@"
 	$@ version
 	$(RM) kail